Bilirubin, Total

The Bilirubin test measures the level of bilirubin in the blood. Bilirubin is a yellow pigment formed from the breakdown of red blood cells. This test is typically divided into total, direct (conjugated), and indirect (unconjugated) bilirubin. Elevated levels can indicate liver dysfunction, bile duct obstruction, or increased red blood cell breakdown.

1. What Is Bilirubin?

• Bilirubin is produced when hemoglobin in red blood cells breaks down.

• The liver processes bilirubin and excretes it through bile into the intestines.

• There are two main forms:

  - Indirect (unconjugated): Not yet processed by the liver.

  - Direct (conjugated): Processed by the liver and ready for excretion.

2. Why Is the Bilirubin Test Performed?

The test is used to:

• Evaluate liver function and detect liver diseases such as hepatitis or cirrhosis.

• Diagnose the cause of jaundice (yellowing of skin and eyes).

• Assess bile duct obstruction or gallbladder disease.

• Monitor newborns for neonatal jaundice.

3. Bilirubin Reference Ranges

• Total Bilirubin: 0.1 – 1.2 mg/dL

• Direct Bilirubin: 0.0 – 0.3 mg/dL

• Indirect Bilirubin: Calculated by subtracting direct from total bilirubin.

4. How to Interpret Bilirubin Results

🔹 Elevated Total Bilirubin:

• May indicate liver disease, bile duct obstruction, or hemolytic anemia.

🔹 Elevated Direct Bilirubin:

• Suggests liver dysfunction or bile duct blockage (e.g., gallstones, tumors).

🔹 Elevated Indirect Bilirubin:

• Often caused by increased red blood cell breakdown or impaired liver uptake (e.g., Gilbert syndrome, hemolysis).

5. What Can Affect Bilirubin Levels?

• Liver diseases (hepatitis, cirrhosis)

• Gallbladder or bile duct conditions (e.g., gallstones, cholestasis)

• Hemolytic anemia or transfusion reactions

• Genetic conditions (e.g., Gilbert syndrome, Crigler-Najjar syndrome)

• Certain medications or alcohol use

6. How to Prepare for the Test

• Fasting may be required for 4–8 hours before the test (follow your provider’s instructions).

• Avoid alcohol and certain medications that affect liver function prior to testing.

7. When to See a Doctor

🚨 Speak to your healthcare provider if you:

• Develop yellowing of the eyes or skin (jaundice)

• Experience dark urine, pale stools, or right upper abdominal pain

• Have a history of liver or gallbladder disease

🔹 Key Takeaways

✅ Bilirubin is a byproduct of red blood cell breakdown processed by the liver.

✅ The test helps assess liver and bile duct function and diagnose jaundice.

✅ Elevated bilirubin levels may suggest liver disease, bile obstruction, or increased hemolysis.

C-Peptide (C-Terminal Insulin)

The C-Peptide test measures the level of C-peptide in the blood. C-peptide is a byproduct released when the pancreas produces insulin. It is used to evaluate how much insulin the body is producing and can help differentiate between type 1 and type 2 diabetes or assess insulin resistance.

1. What Is C-Peptide?

• C-peptide (connecting peptide) is released in equal amounts to insulin when proinsulin splits into insulin and C-peptide in the pancreas.

• Unlike insulin, C-peptide is not affected by insulin injections, making it a useful marker for natural insulin production.

• It helps assess pancreatic beta-cell function.

2. Why Is the C-Peptide Test Performed?

This test is used to:

• Determine whether the body is producing insulin.

• Differentiate between type 1 diabetes (low or absent C-peptide) and type 2 diabetes (normal or high C-peptide).

• Evaluate the cause of low blood sugar (hypoglycemia).

• Monitor insulinoma (insulin-producing tumor).

• Assess beta-cell function in diabetes management or after pancreas transplant.

3. C-Peptide Reference Range

• Fasting: 0.5 – 2.0 ng/mL

• Levels can vary depending on lab methods and whether the test is done fasting or post-glucose intake.

4. How to Interpret C-Peptide Results

🔹 Low C-Peptide:

• Suggests reduced insulin production, as seen in type 1 diabetes or advanced type 2 diabetes.

• May also occur after removal of the pancreas or due to autoimmune destruction of beta cells.

🔹 High C-Peptide:

• Suggests high insulin production, which may occur in type 2 diabetes, insulin resistance, or insulinoma.

• May also be elevated in people taking sulfonylureas or with certain kidney disorders.

5. What Can Affect C-Peptide Levels?

• Type of diabetes and treatment (insulin vs. oral medications)

• Glucose levels at the time of testing

• Kidney function (C-peptide is cleared by the kidneys)

• Medications affecting insulin production (e.g., sulfonylureas)

6. How Is the Test Performed?

• A blood sample is taken, usually after fasting or sometimes after a glucose challenge.

• It may be ordered alongside blood glucose and insulin tests for a more complete assessment.

7. When to See a Doctor

🚨 Contact your healthcare provider if you:

• Have unexplained low or high blood sugar.

• Are newly diagnosed with diabetes and need to determine type.

• Are being evaluated for pancreatic function or insulin-producing tumors.

🔹 Key Takeaways

✅ C-peptide is a reliable marker of your body’s natural insulin production.

✅ It helps distinguish between different types of diabetes and assess beta-cell function.

✅ Testing is useful for diagnosis, management, and treatment planning in diabetes care.

C-Reactive Protein (CRP)

The C-Reactive Protein (CRP) test measures the level of CRP in the blood. CRP is a protein produced by the liver in response to inflammation. It is a nonspecific marker used to detect inflammation, infection, and monitor disease activity in conditions such as autoimmune disorders, cardiovascular disease, and infections.

1. What Is C-Reactive Protein?

• CRP is part of the body's immune response and is produced by the liver when there is inflammation in the body.

• It rises rapidly in response to infection, trauma, or tissue injury and returns to normal when the inflammation subsides.

• It is a sensitive but nonspecific marker—elevated CRP does not pinpoint the exact cause of inflammation.

2. Why Is the CRP Test Performed?

This test is used to:

• Detect acute inflammation due to infection, trauma, or surgery.

• Monitor chronic inflammatory conditions such as rheumatoid arthritis or lupus.

• Assess risk for cardiovascular disease (high-sensitivity CRP or hs-CRP).

• Evaluate the effectiveness of treatment for inflammation-related conditions.

3. CRP Reference Ranges

• Standard CRP:

  - Normal: < 10 mg/L

  - Mild elevation: 10 – 40 mg/L (may suggest mild inflammation or viral infection)

  - Moderate to high: > 40 mg/L (may suggest bacterial infection or significant inflammation)

• High-sensitivity CRP (hs-CRP) for cardiovascular risk:

  - Low risk: < 1.0 mg/L

  - Average risk: 1.0 – 3.0 mg/L

  - High risk: > 3.0 mg/L

4. How to Interpret CRP Results

🔹 Elevated CRP:

• May indicate infection, inflammatory disease, injury, or chronic illness.

• Persistently elevated CRP may be associated with an increased risk of cardiovascular events.

🔹 Normal or Low CRP:

• Indicates little or no current inflammation.

• May suggest effective treatment or resolution of an acute condition.

5. What Can Affect CRP Levels?

• Acute infections or injuries

• Chronic diseases (e.g., rheumatoid arthritis, lupus, inflammatory bowel disease)

• Obesity, smoking, and poor diet

• Heart disease or recent heart attack

• Use of anti-inflammatory medications or statins

6. How Is the Test Performed?

• A blood sample is drawn from a vein.

• No special preparation is typically required unless otherwise instructed.

7. When to See a Doctor

🚨 Contact your healthcare provider if you:

• Have persistent or unexplained elevated CRP levels.

• Are experiencing symptoms of infection, chronic inflammation, or heart disease.

• Are being monitored for an inflammatory or autoimmune condition.

🔹 Key Takeaways

✅ CRP is a nonspecific marker of inflammation and infection.

✅ It is useful for diagnosing and monitoring inflammatory conditions and cardiovascular risk.

✅ Elevated CRP should be interpreted with other clinical findings for accurate diagnosis.

Calcitonin

The Calcitonin test measures the level of calcitonin, a hormone produced by the C-cells of the thyroid gland. Calcitonin plays a minor role in calcium regulation, but it is primarily used as a tumor marker for diagnosing and monitoring medullary thyroid carcinoma (MTC), a rare type of thyroid cancer.

1. What Is Calcitonin?

• Calcitonin is a hormone secreted by the parafollicular C-cells of the thyroid gland.

• It helps regulate calcium and phosphate levels in the blood by inhibiting bone resorption.

• Although it has limited importance in daily calcium balance, it serves as a key marker for certain thyroid conditions.

2. Why Is the Calcitonin Test Performed?

This test is used to:

• Detect medullary thyroid carcinoma (MTC), including early or inherited forms (MEN 2 syndrome).

• Monitor patients after thyroid cancer treatment for recurrence.

• Evaluate thyroid nodules to determine if further testing is needed.

• Screen family members of patients with hereditary MTC.

3. Calcitonin Reference Ranges

• Normal ranges vary by lab and sex:

  - Men: < 10 pg/mL

  - Women: < 5 pg/mL

• Higher values may be considered normal in newborns or during pregnancy.

4. How to Interpret Calcitonin Results

🔹 Elevated Calcitonin:

• Strongly associated with medullary thyroid carcinoma (MTC)

• May also occur in conditions such as C-cell hyperplasia, chronic renal failure, or certain lung cancers

🔹 Normal Calcitonin:

• Suggests low likelihood of MTC but may not completely rule it out, especially in early stages

5. What Can Affect Calcitonin Levels?

• Medullary thyroid carcinoma or C-cell hyperplasia

• Kidney disease

• Smoking or proton pump inhibitors (e.g., omeprazole)

• Other cancers (e.g., small cell lung cancer)

6. How Is the Test Performed?

• A blood sample is drawn, usually without the need for fasting.

• In some cases, a stimulation test using calcium or pentagastrin may be done to provoke calcitonin release.

7. When to See a Doctor

🚨 Contact your healthcare provider if you:

• Have a thyroid nodule with elevated calcitonin

• Have a family history of medullary thyroid carcinoma or MEN 2 syndrome

• Experience symptoms such as a lump in the neck, difficulty swallowing, or hoarseness

🔹 Key Takeaways

✅ Calcitonin is a thyroid hormone used as a tumor marker for medullary thyroid carcinoma (MTC).

✅ Elevated levels may indicate thyroid cancer or other medical conditions requiring further evaluation.

✅ The test is essential in diagnosing, monitoring, and screening for MTC and C-cell disorders.

Calcium

The Calcium test measures the level of calcium in the blood. Calcium is a vital mineral essential for bone health, muscle function, nerve transmission, and hormone secretion. The test helps evaluate bone disorders, kidney function, and parathyroid gland activity.

1. What Is Calcium?

• Calcium is the most abundant mineral in the body, with over 99% stored in bones and teeth.

• The remaining calcium circulates in the blood and is tightly regulated by the parathyroid hormone (PTH), vitamin D, and calcitonin.

• Blood calcium exists in two forms:

  - Bound calcium: Attached to proteins (like albumin).

  - Free (ionized) calcium: The biologically active form.

2. Why Is the Calcium Test Performed?

This test is used to:

• Evaluate bone health and screen for osteoporosis or calcium imbalances.

• Monitor kidney function and chronic kidney disease (CKD).

• Diagnose parathyroid gland disorders (e.g., hyperparathyroidism).

• Assess symptoms such as muscle cramps, tingling, or confusion.

3. Calcium Reference Ranges

• Total Calcium (serum): 8.5 – 10.5 mg/dL

• Ionized Calcium: 4.4 – 5.4 mg/dL

• These ranges may vary slightly by lab. Total calcium can be influenced by albumin levels.

4. How to Interpret Calcium Results

🔹 Elevated Calcium (Hypercalcemia):

• May indicate hyperparathyroidism, certain cancers, excessive vitamin D intake, or dehydration.

• Symptoms include fatigue, nausea, constipation, kidney stones, and confusion.

🔹 Low Calcium (Hypocalcemia):

• May result from hypoparathyroidism, kidney disease, vitamin D deficiency, or magnesium imbalance.

• Symptoms include muscle cramps, tingling, seizures, or heart rhythm problems.

5. What Can Affect Calcium Levels?

• Parathyroid gland disorders

• Vitamin D levels

• Kidney function

• Certain cancers (e.g., bone metastases)

• Medications (e.g., diuretics, lithium, calcium supplements)

6. How Is the Test Performed?

• A blood sample is drawn, usually with no special preparation required for total calcium.

• Ionized calcium may require fasting and special handling.

7. When to See a Doctor

🚨 Contact your healthcare provider if you:

• Have symptoms of calcium imbalance (e.g., cramps, fatigue, mental confusion).

• Are being treated for kidney disease, thyroid/parathyroid disorders, or certain cancers.

• Have abnormal calcium test results or are at risk for osteoporosis.

🔹 Key Takeaways

✅ Calcium is essential for bone strength, muscle function, and nerve signaling.

✅ Abnormal levels may indicate endocrine, kidney, or nutritional disorders.

✅ Both total and ionized calcium may be tested depending on clinical needs.

Carbon Dioxide, Total (CO₂)

The Carbon Dioxide (CO₂), Total test measures the amount of carbon dioxide in the blood, primarily in the form of bicarbonate (HCO₃⁻). This test is often part of a basic or comprehensive metabolic panel and helps evaluate your body's acid-base balance (pH) and electrolyte status.

1. What Is Carbon Dioxide (CO₂), Total?

• Total CO₂ primarily reflects the level of bicarbonate in the blood, which helps buffer acids and maintain normal pH.

• It also includes small amounts of dissolved CO₂ gas and carbonic acid.

• Bicarbonate is regulated by the kidneys and lungs to maintain acid-base homeostasis.

2. Why Is the Total CO₂ Test Performed?

This test is used to:

• Evaluate acid-base balance (metabolic acidosis or alkalosis).

• Monitor kidney and lung function.

• Detect electrolyte disturbances (especially related to sodium, potassium, or chloride).

• Assist in diagnosing chronic diseases such as kidney failure, diabetic ketoacidosis, or COPD.

3. Total CO₂ Reference Range

• Normal range: 23 – 30 mmol/L (millimoles per liter)

• Slight variations may occur depending on the laboratory and patient conditions.

4. How to Interpret Total CO₂ Results

🔹 Low CO₂ (Bicarbonate):

• May indicate metabolic acidosis (too much acid or loss of bicarbonate).

• Causes include kidney disease, lactic acidosis, diabetic ketoacidosis, or diarrhea.

🔹 High CO₂ (Bicarbonate):

• May suggest metabolic alkalosis (too little acid or excess bicarbonate).

• Causes include vomiting, dehydration, or use of diuretics.

5. What Can Affect CO₂ Levels?

• Respiratory conditions (COPD, asthma)

• Kidney disease or renal tubular acidosis

• Endocrine disorders (e.g., Cushing syndrome)

• Use of medications such as antacids or diuretics

• Severe infections or metabolic conditions

6. How Is the Test Performed?

• A blood sample is drawn from a vein, usually as part of a metabolic panel.

• No special preparation is typically required unless specified by your provider.

7. When to See a Doctor

🚨 Contact your healthcare provider if you:

• Have abnormal CO₂ levels or symptoms such as shortness of breath, fatigue, or confusion.

• Are managing a condition like kidney disease, diabetes, or chronic lung disease.

• Experience persistent vomiting or diarrhea, which can affect acid-base balance.

🔹 Key Takeaways

✅ Total CO₂ reflects the bicarbonate level in the blood and helps evaluate acid-base status.

✅ Abnormal levels may point to respiratory or metabolic disorders requiring further investigation.

✅ CO₂ is usually tested alongside other electrolytes to give a full picture of metabolic health.

Carcinoembryonic Antigen (CEA)

The Carcinoembryonic Antigen (CEA) test measures the level of CEA, a protein that is normally present at very low levels in healthy adults. CEA is considered a tumor marker, and elevated levels may be associated with certain cancers, especially colorectal cancer. It is commonly used to monitor treatment response and detect cancer recurrence.

1. What Is CEA?

• CEA is a glycoprotein involved in cell adhesion and is normally produced during fetal development.

• In healthy adults, CEA levels are usually very low or undetectable.

• Some cancers may produce large amounts of CEA, making it useful for cancer detection and monitoring.

2. Why Is the CEA Test Performed?

This test is used to:

• Monitor colorectal cancer after diagnosis and during treatment.

• Detect cancer recurrence after surgery or chemotherapy.

• Sometimes used to assess other cancers (e.g., lung, breast, pancreatic, or stomach).

• Occasionally ordered when cancer is suspected based on symptoms and imaging studies.

3. CEA Reference Ranges

• Non-smokers: < 3.0 ng/mL

• Smokers: < 5.0 ng/mL

• Levels above the normal range may suggest cancer or other conditions, but CEA is not cancer-specific.

4. How to Interpret CEA Results

🔹 Elevated CEA:

• May indicate cancer of the colon, rectum, or other organs (especially if levels continue to rise).

• May also occur in non-cancerous conditions like liver disease, inflammatory bowel disease, or smoking.

🔹 Declining CEA:

• Suggests a positive response to treatment (e.g., surgery or chemotherapy).

🔹 Rising CEA after treatment:

• May signal recurrence or spread (metastasis) of cancer.

5. What Can Affect CEA Levels?

• Smoking (can cause moderately elevated levels)

• Liver disease (e.g., cirrhosis, hepatitis)

• Infections and inflammatory conditions (e.g., pancreatitis, IBD)

• Certain benign tumors

6. How Is the Test Performed?

• A blood sample is taken from a vein, typically requiring no special preparation.

• Serial measurements may be taken over time to monitor trends.

7. When to See a Doctor

🚨 Contact your healthcare provider if you:

• Have a known cancer diagnosis and rising CEA levels.

• Are being monitored for cancer recurrence after treatment.

• Have persistent symptoms (e.g., weight loss, abdominal pain, blood in stool) along with elevated CEA.

🔹 Key Takeaways

✅ CEA is a tumor marker primarily used for monitoring colorectal and other cancers.

✅ It is not used for cancer screening due to limited specificity and sensitivity.

✅ Rising or falling levels help guide treatment decisions and follow-up care.

Chloride

The Chloride test measures the level of chloride, an important electrolyte, in the blood. Chloride helps maintain fluid balance, acid-base balance, and proper muscle and nerve function. It is usually tested as part of an electrolyte panel or comprehensive metabolic panel (CMP).

1. What Is Chloride?

• Chloride is a negatively charged electrolyte (anion) that works closely with sodium, potassium, and bicarbonate.

• It helps regulate the body's fluid levels, blood pressure, and pH balance.

• Most chloride comes from dietary salt (sodium chloride) and is absorbed in the intestines.

2. Why Is the Chloride Test Performed?

This test is used to:

• Evaluate electrolyte and acid-base balance in the body.

• Help diagnose dehydration, kidney disease, or metabolic disorders.

• Monitor people with conditions such as heart failure, lung disease, or prolonged vomiting.

• Assess the effects of medications like diuretics.

3. Chloride Reference Range

• Normal range: 96 – 106 mmol/L

• Reference values may vary slightly between laboratories.

4. How to Interpret Chloride Results

🔹 Elevated Chloride (Hyperchloremia):

• May occur in dehydration, kidney disease, metabolic acidosis, or respiratory alkalosis.

• Can also result from excessive intake of saline or salt-containing IV fluids.

🔹 Low Chloride (Hypochloremia):

• May occur with vomiting, diarrhea, congestive heart failure, or chronic respiratory acidosis.

• May also be caused by diuretics or adrenal gland disorders (e.g., Addison’s disease).

5. What Can Affect Chloride Levels?

• Fluid loss from vomiting, sweating, or diarrhea

• Kidney dysfunction or failure

• Hormonal imbalances (e.g., aldosterone deficiency)

• Overuse of bicarbonate-containing antacids

• IV fluids and certain medications (e.g., diuretics)

6. How Is the Test Performed?

• A blood sample is drawn from a vein, typically as part of an electrolyte or metabolic panel.

• No special preparation is usually required.

7. When to See a Doctor

🚨 Contact your healthcare provider if you:

• Have abnormal chloride levels or symptoms such as weakness, confusion, or irregular heartbeat.

• Are on medications that affect electrolyte balance (e.g., diuretics).

• Experience ongoing fluid loss or dehydration.

🔹 Key Takeaways

✅ Chloride is an essential electrolyte that helps regulate fluid and acid-base balance.

✅ Both high and low levels may indicate underlying metabolic or kidney-related issues.

✅ It is often assessed alongside sodium, potassium, and bicarbonate for a complete picture.

Cholesterol, Total

The Total Cholesterol test measures the overall amount of cholesterol in the blood. Cholesterol is a waxy, fat-like substance that is vital for building cells, producing hormones, and aiding digestion. However, high levels of cholesterol are associated with an increased risk of heart disease and stroke. This test is typically part of a lipid panel.

1. What Is Total Cholesterol?

• Total cholesterol includes the sum of:

  - Low-density lipoprotein (LDL) cholesterol – often called 'bad' cholesterol

  - High-density lipoprotein (HDL) cholesterol – known as 'good' cholesterol

  - Very low-density lipoprotein (VLDL) and other lipid components

• Cholesterol is produced by the liver and also obtained from dietary sources.

2. Why Is the Total Cholesterol Test Performed?

This test is used to:

• Screen for risk of cardiovascular disease (CVD).

• Monitor response to cholesterol-lowering treatment (e.g., statins).

• Evaluate lipid status as part of a routine health checkup.

• Identify individuals at risk for stroke or atherosclerosis.

3. Total Cholesterol Reference Ranges

• Desirable: < 200 mg/dL

• Borderline high: 200 – 239 mg/dL

• High: ≥ 240 mg/dL

• Ideal levels depend on age, sex, and overall cardiovascular risk profile.

4. How to Interpret Total Cholesterol Results

🔹 Desirable (< 200 mg/dL):

• Indicates lower risk for heart disease.

🔹 Borderline High (200–239 mg/dL):

• May require closer monitoring and lifestyle changes.

🔹 High (≥ 240 mg/dL):

• Associated with increased risk of heart attack, stroke, and atherosclerosis.

5. What Can Affect Cholesterol Levels?

• Diet high in saturated fats and trans fats

• Physical inactivity

• Obesity or being overweight

• Smoking or excessive alcohol use

• Genetics (e.g., familial hypercholesterolemia)

• Certain medical conditions (e.g., hypothyroidism, diabetes)

6. How to Maintain Healthy Cholesterol Levels

• Eat a heart-healthy diet (rich in fruits, vegetables, whole grains, and lean protein)

• Exercise regularly (at least 150 minutes of moderate aerobic activity per week)

• Avoid tobacco and limit alcohol

• Maintain a healthy weight

• Take cholesterol-lowering medications if prescribed

7. When to See a Doctor

🚨 Contact your healthcare provider if you:

• Have total cholesterol ≥ 240 mg/dL or other abnormal lipid values

• Have a family history of high cholesterol or early heart disease

• Are at risk for cardiovascular conditions or are already on treatment

🔹 Key Takeaways

✅ Total cholesterol reflects the combined levels of HDL, LDL, and other lipid particles in the blood.

✅ High cholesterol increases the risk of heart disease and stroke.

✅ Lifestyle changes and/or medication can help manage cholesterol and protect heart health.

This Cortisol Stress Hormone test can be performed in the morning, or in the afternoon and evening. There is a difference between the two times. You may need to have blood drawn at a specific time.

Cortisol Stress Hormone Test (AM)

The Cortisol (AM) test measures the level of cortisol, a key stress hormone, in the blood during the early morning hours. Cortisol is produced by the adrenal glands and plays a crucial role in regulating metabolism, immune response, blood pressure, and the body’s response to stress.

1. What Is Cortisol?

• Cortisol is a steroid hormone produced by the adrenal glands, located above the kidneys.

• It follows a daily rhythm—highest in the early morning and lowest around midnight.

• It helps control blood sugar, reduce inflammation, regulate metabolism, and manage stress responses.

2. Why Is the Cortisol AM Test Performed?

This test is used to:

• Evaluate adrenal gland function.

• Diagnose disorders such as Cushing’s syndrome (high cortisol) or Addison’s disease (low cortisol).

• Investigate symptoms like fatigue, weakness, weight changes, or blood pressure abnormalities.

• Monitor adrenal function in patients using steroid medications.

3. Cortisol AM Reference Range

• Normal morning range: 6 – 23 mcg/dL

• Optimal cortisol levels are typically measured between 6 a.m. and 8 a.m. due to diurnal rhythm.

4. How to Interpret Cortisol AM Results

🔹 Elevated Cortisol:

• May indicate Cushing’s syndrome, stress, pituitary tumors, or adrenal tumors.

• May also result from medications (e.g., corticosteroids) or intense physical/emotional stress.

🔹 Low Cortisol:

• Suggests adrenal insufficiency (e.g., Addison’s disease) or pituitary dysfunction.

• May be accompanied by fatigue, low blood pressure, and weight loss.

5. What Can Affect Cortisol Levels?

• Time of day (AM levels are naturally higher)

• Stress (emotional or physical)

• Medications (e.g., corticosteroids, estrogen)

• Sleep patterns or shift work

• Chronic illness or malnutrition

6. How Is the Test Performed?

• A blood sample is drawn, typically between 6 a.m. and 8 a.m. to capture peak cortisol levels.

• No fasting is required, but your provider may give specific instructions.

7. When to See a Doctor

🚨 Contact your healthcare provider if you:

• Have persistent fatigue, dizziness, weight loss, or blood pressure issues.

• Suspect an adrenal disorder or are using steroid medications long-term.

• Experience unexplained changes in mood, energy, or immune function.

🔹 Key Takeaways

✅ The Cortisol AM test evaluates adrenal gland health and helps diagnose hormone disorders.

✅ Elevated levels may signal Cushing’s syndrome; low levels may indicate Addison’s disease.

✅ Testing is time-sensitive and should be performed in the early morning.

 

Cortisol Stress Hormone Test (PM)

The Cortisol (PM) test measures cortisol levels in the blood during the late afternoon or evening. Cortisol is a steroid hormone produced by the adrenal glands and plays an essential role in the body’s stress response, metabolism, blood pressure regulation, and immune system. Cortisol levels follow a diurnal pattern and are typically lower in the evening.

1. What Is Cortisol?

• Cortisol is produced by the adrenal cortex and regulated by the hypothalamic-pituitary-adrenal (HPA) axis.

• It helps maintain blood glucose, supports metabolism, reduces inflammation, and assists the body in responding to stress.

• Cortisol levels normally peak in the early morning and decrease throughout the day.

2. Why Is the Cortisol PM Test Performed?

This test is used to:

• Evaluate the diurnal rhythm of cortisol secretion.

• Help diagnose adrenal disorders such as Cushing’s syndrome or Addison’s disease.

• Monitor adrenal function in patients undergoing steroid therapy or hormone replacement.

• Assist in identifying abnormalities in cortisol suppression or regulation.

3. Cortisol PM Reference Range

• Normal evening range: 3 – 10 mcg/dL

• Levels are expected to be significantly lower than morning (AM) values.

4. How to Interpret Cortisol PM Results

🔹 Elevated PM Cortisol:

• May suggest a disruption in normal cortisol rhythm, often seen in Cushing’s syndrome.

• May also result from stress, depression, or steroid medication use.

🔹 Low PM Cortisol:

• Typically expected, but abnormally low levels may indicate adrenal insufficiency or Addison’s disease.

5. What Can Affect PM Cortisol Levels?

• Stress and psychological conditions (e.g., anxiety, depression)

• Sleep disorders or shift work

• Chronic illness or inflammation

• Use of corticosteroid medications

• Pituitary or adrenal gland dysfunction

6. How Is the Test Performed?

• A blood sample is taken, usually between 4 p.m. and 6 p.m., to assess cortisol during its natural daily decline.

• No fasting is typically required unless instructed by your healthcare provider.

7. When to See a Doctor

🚨 Consult your healthcare provider if you:

• Show signs of hormone imbalance (e.g., weight gain, fatigue, mood swings, high blood pressure).

• Are being evaluated for adrenal disorders.

• Experience symptoms that differ in intensity from morning to evening.

🔹 Key Takeaways

✅ The Cortisol PM test assesses cortisol levels during the body's natural evening decline.

✅ Elevated PM cortisol may indicate adrenal hyperfunction (e.g., Cushing’s syndrome).

✅ The test helps evaluate the daily pattern of cortisol and overall adrenal gland health.

Creatine Kinase (CK), Total

The Creatine Kinase (CK), Total test measures the overall level of CK in the blood. CK is an enzyme found mainly in the heart, brain, and skeletal muscles. High levels can indicate muscle damage, inflammation, or disorders affecting muscle or heart function. This test is often used to detect muscle diseases or monitor conditions like heart attack or rhabdomyolysis.

1. What Is Creatine Kinase (CK)?

• CK is an enzyme involved in energy production within muscle cells.

• There are three major types of CK:

  - CK-MM: Found in skeletal muscles

  - CK-MB: Found mostly in heart muscle

  - CK-BB: Found primarily in brain tissue

• The CK Total test measures all isoforms combined.

2. Why Is the CK Total Test Performed?

This test is used to:

• Detect muscle injury, inflammation, or breakdown (e.g., rhabdomyolysis).

• Evaluate chest pain or suspected heart attack (with CK-MB follow-up).

• Diagnose neuromuscular disorders (e.g., muscular dystrophy).

• Monitor effects of medications that may damage muscles (e.g., statins).

3. CK Total Reference Range

• Normal range: 22 – 198 U/L (units per liter)

• Reference ranges vary slightly by age, sex, and laboratory.

4. How to Interpret CK Results

🔹 Elevated CK:

• May indicate recent or ongoing muscle injury, strenuous exercise, or heart damage.

• Extremely high levels are seen in rhabdomyolysis, which can lead to kidney damage.

🔹 Mildly Elevated CK:

• Common in individuals after exercise or physical labor.

🔹 Low CK:

• Typically not a concern unless associated with muscle wasting or long-term illness.

5. What Can Affect CK Levels?

• Intense exercise or muscle trauma

• Heart attack or myocarditis

• Inflammatory muscle diseases (e.g., polymyositis, dermatomyositis)

• Medications like statins, fibrates, or colchicine

• Alcohol abuse, seizures, or prolonged immobilization

6. How Is the Test Performed?

• A blood sample is drawn from a vein, typically requiring no fasting or special preparation.

• If heart damage is suspected, CK-MB or troponin tests may also be ordered.

7. When to See a Doctor

🚨 Speak to your healthcare provider if you:

• Experience unexplained muscle pain, weakness, or swelling.

• Have elevated CK levels on a recent test.

• Are on medications known to affect muscles or have kidney disease symptoms.

🔹 Key Takeaways

✅ CK is a key enzyme used to detect muscle and heart damage.

✅ Elevated levels may result from injury, overuse, medications, or disease.

✅ Timely diagnosis and treatment can help prevent complications such as kidney injury from rhabdomyolysis.

Creatinine

The Creatinine test measures the level of creatinine in the blood. Creatinine is a waste product produced by muscle metabolism and excreted by the kidneys. It is a reliable indicator of kidney function. Elevated or reduced creatinine levels can help assess how well the kidneys are filtering waste from the blood.

1. What Is Creatinine?

• Creatinine is produced from the breakdown of creatine, a molecule important for energy in muscles.

• It is filtered from the blood by the kidneys and excreted in the urine.

• Creatinine levels remain relatively stable in individuals with normal kidney function.

2. Why Is the Creatinine Test Performed?

This test is used to:

• Assess kidney function.

• Help diagnose and monitor chronic kidney disease (CKD).

• Monitor the effects of medications that may impair kidney function.

• Evaluate dehydration, muscle disorders, or severe infections.

3. Creatinine Reference Range

• Normal range (adults):

  - Men: 0.7 – 1.3 mg/dL

  - Women: 0.6 – 1.1 mg/dL

• Reference values may vary slightly depending on lab, age, sex, and muscle mass.

4. How to Interpret Creatinine Results

🔹 Elevated Creatinine:

• Suggests impaired kidney function or kidney disease.

• May also occur with dehydration, urinary tract obstruction, or certain medications.

🔹 Low Creatinine:

• May be seen in reduced muscle mass, advanced liver disease, or pregnancy.

• Usually not a concern unless accompanied by other abnormal lab values.

5. What Can Affect Creatinine Levels?

• Kidney disease or injury

• Dehydration or fluid loss

• Muscle mass and physical activity

• Certain medications (e.g., NSAIDs, ACE inhibitors, chemotherapy)

• High protein diet or creatine supplements

6. How Is the Test Performed?

• A blood sample is taken from a vein.

• Sometimes, a 24-hour urine collection is also ordered to measure creatinine clearance.

7. When to See a Doctor

🚨 Contact your healthcare provider if you:

• Have abnormal creatinine levels on routine testing.

• Experience signs of kidney problems such as fatigue, swelling, or changes in urination.

• Take medications that may affect kidney function.

🔹 Key Takeaways

✅ Creatinine is a key indicator of kidney function and health.

✅ Elevated levels may suggest kidney impairment or dehydration.

✅ Regular monitoring is important for individuals with kidney disease, diabetes, or hypertension.

DHEA Sulfate (Dehydroepiandrosterone Sulfate)

The DHEA Sulfate test measures the level of dehydroepiandrosterone sulfate (DHEA-S) in the blood. DHEA-S is a hormone produced primarily by the adrenal glands and serves as a precursor to male and female sex hormones, including testosterone and estrogen. This test helps evaluate adrenal gland function and diagnose hormone-related disorders.

1. What Is DHEA Sulfate?

• DHEA-S is a sulfated form of DHEA, making it more stable and easier to measure in the blood.

• It is one of the most abundant circulating steroid hormones and is involved in the production of androgens and estrogens.

• DHEA-S levels naturally decline with age and can be influenced by adrenal or pituitary disorders.

2. Why Is the DHEA-S Test Performed?

This test is used to:

• Evaluate adrenal gland function.

• Diagnose adrenal tumors, congenital adrenal hyperplasia, or polycystic ovary syndrome (PCOS).

• Investigate signs of excess androgen production (e.g., hirsutism, acne, irregular periods).

• Help determine the cause of early puberty or delayed puberty in children.

3. DHEA-S Reference Ranges

• Reference ranges vary by age and sex. Typical adult values:

  - Men: 280 – 640 µg/dL

  - Women: 65 – 380 µg/dL

• Levels are highest in early adulthood and decline with age.

4. How to Interpret DHEA-S Results

🔹 Elevated DHEA-S:

• May suggest adrenal tumors, PCOS, or congenital adrenal hyperplasia.

• Can also be caused by certain medications or supplements containing DHEA.

🔹 Low DHEA-S:

• May indicate adrenal insufficiency (Addison’s disease) or hypopituitarism.

• Levels naturally decline with age.

5. What Can Affect DHEA-S Levels?

• Age and sex (natural decline with age)

• Adrenal gland health and hormone production

• Pituitary function (regulates adrenal activity)

• Medications (e.g., glucocorticoids, DHEA supplements, insulin)

• Stress or chronic illness

6. How Is the Test Performed?

• A blood sample is taken from a vein, usually in the morning.

• No special preparation is typically required unless advised by your provider.

7. When to See a Doctor

🚨 Contact your healthcare provider if you:

• Show symptoms of hormone imbalance, such as irregular periods, hair loss, acne, or infertility.

• Have abnormal DHEA-S levels that may indicate adrenal or pituitary disorders.

• Are undergoing evaluation for early or delayed puberty.

🔹 Key Takeaways

✅ DHEA-S is a stable hormone marker used to assess adrenal and hormonal health.

✅ Elevated levels may indicate adrenal overactivity or androgen excess.

✅ Low levels may be linked to adrenal insufficiency or aging. Interpretation depends on clinical context.

eGFR (Estimated Glomerular Filtration Rate – Calculation)

The eGFR (Estimated Glomerular Filtration Rate) test is a calculated value used to assess how well the kidneys are filtering blood. It estimates kidney function based on serum creatinine levels, age, sex, and sometimes race. eGFR is a key tool in diagnosing and monitoring chronic kidney disease (CKD).

1. What Is eGFR?

• eGFR estimates the rate at which the kidneys filter waste products from the blood (measured in mL/min/1.73 m²).

• It is calculated using mathematical formulas such as the CKD-EPI or MDRD equations.

• The most commonly used variables include serum creatinine, age, sex, and sometimes race.

2. Why Is the eGFR Test Performed?

This test is used to:

• Assess overall kidney function.

• Detect early signs of chronic kidney disease (CKD).

• Monitor progression of CKD or kidney damage over time.

• Guide treatment decisions for patients with diabetes, hypertension, or kidney disease.

3. eGFR Reference Ranges and Stages of CKD

• Normal: ≥ 90 mL/min/1.73 m²

• Mild decrease: 60 – 89 mL/min/1.73 m²

• Moderate decrease: 30 – 59 mL/min/1.73 m² (CKD Stage 3)

• Severe decrease: 15 – 29 mL/min/1.73 m² (CKD Stage 4)

• Kidney failure: < 15 mL/min/1.73 m² (CKD Stage 5 – may require dialysis)

4. How to Interpret eGFR Results

🔹 eGFR ≥ 90:

• Normal kidney function if no other markers of damage are present.

🔹 eGFR 60–89:

• Mildly reduced function—monitor if other risk factors (e.g., diabetes, proteinuria) are present.

🔹 eGFR < 60:

• Indicates chronic kidney disease. Requires closer monitoring and potential intervention.

5. What Can Affect eGFR Results?

• Muscle mass (high in muscular individuals, low in elderly or malnourished)

• Certain medications (e.g., ACE inhibitors, NSAIDs)

• Hydration status and recent protein intake

• Acute illness or infections

• Incorrect blood sampling or lab error

6. How Is the eGFR Calculated?

• eGFR is not directly measured but calculated from serum creatinine using established formulas.

• No special preparation is usually needed; a standard blood draw for creatinine suffices.

7. When to See a Doctor

🚨 Contact your healthcare provider if you:

• Have a consistently low eGFR (< 60) across multiple tests.

• Experience symptoms of kidney disease (e.g., fatigue, swelling, foamy urine).

• Have diabetes, hypertension, or a family history of kidney disease.

🔹 Key Takeaways

✅ eGFR is a critical marker of kidney function calculated from creatinine and other factors.

✅ Values < 60 mL/min/1.73 m² may indicate chronic kidney disease.

✅ Monitoring eGFR regularly helps detect kidney issues early and guide management.