Parathyroid Hormone (PTH)

The Parathyroid Hormone (PTH) test measures the amount of PTH in the blood. PTH is a hormone produced by the parathyroid glands that helps regulate calcium and phosphate levels in the blood and bones. This test is commonly used to evaluate parathyroid gland function and diagnose the causes of abnormal calcium levels.

1. What Is PTH?

• PTH is secreted by four small parathyroid glands located behind the thyroid gland.

• It plays a critical role in maintaining calcium balance by:

  - Increasing calcium absorption from the intestine (via vitamin D activation)

  - Stimulating calcium release from bones

  - Reducing calcium excretion by the kidneys

• PTH also lowers phosphate levels by increasing phosphate excretion in urine.

2. Why Is the PTH Test Performed?

This test is used to:

• Diagnose hyperparathyroidism or hypoparathyroidism.

• Investigate the cause of high or low calcium levels.

• Monitor treatment in individuals with parathyroid disorders or chronic kidney disease.

• Evaluate bone health and calcium metabolism.

3. PTH Reference Range

• Normal range: 10 – 65 pg/mL (varies by lab and testing method)

• Interpretation depends on corresponding calcium and vitamin D levels.

4. Interpreting PTH Results

🔹 High PTH (Hyperparathyroidism):

• Primary: Due to parathyroid gland overactivity (e.g., benign tumor).

• Secondary: Response to low calcium (e.g., vitamin D deficiency, chronic kidney disease).

• Tertiary: Seen in chronic renal failure with long-standing secondary hyperparathyroidism.

🔹 Low PTH (Hypoparathyroidism):

• May result from parathyroid gland damage, autoimmune disorders, or low magnesium levels.

• Leads to low calcium and high phosphate levels.

5. What Can Affect PTH Levels?

• Blood calcium and phosphate levels

• Vitamin D status and kidney function

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

• Surgery involving the thyroid or parathyroid glands

6. How Is the Test Performed?

• A blood sample is drawn, often in conjunction with calcium and vitamin D levels.

• Fasting may be required, especially if calcium or phosphorus is being tested.

7. When to See a Doctor

🚨 Contact your healthcare provider if you:

• Have symptoms of calcium imbalance (e.g., muscle cramps, bone pain, fatigue, tingling).

• Show abnormal blood calcium, phosphorus, or vitamin D levels.

• Are being evaluated for kidney disease, osteoporosis, or parathyroid disorders.

🔹 Key Takeaways

✅ PTH is essential for regulating calcium and phosphate in the body.

✅ Abnormal levels can point to parathyroid dysfunction or metabolic imbalances.

✅ Proper interpretation requires consideration of calcium, phosphate, and vitamin D levels.

Description unavailable. Sorry!

Phosphorus

The Phosphorus test measures the level of phosphate in the blood. Phosphorus is an essential mineral involved in the formation of bones and teeth, energy production, and cell function. Most phosphorus in the body is found in the bones, with a small amount circulating in the blood as phosphate. Abnormal phosphorus levels may indicate issues with the kidneys, bones, hormones, or nutrition.

1. What Is Phosphorus?

• Phosphorus is a mineral primarily stored in bones, with the remainder found in cells and blood as phosphate.

• It plays a critical role in energy metabolism (ATP), bone strength, nerve signaling, and acid-base balance.

• Phosphorus levels are regulated by the kidneys, vitamin D, and parathyroid hormone (PTH).

2. Why Is the Phosphorus Test Performed?

This test is used to:

• Evaluate kidney function and calcium-phosphate balance.

• Diagnose causes of bone disorders, vitamin D imbalances, or parathyroid problems.

• Monitor phosphorus levels in people with chronic kidney disease or those receiving dialysis.

• Assess nutritional status, especially in cases of malnutrition or alcoholism.

3. Phosphorus Reference Range

• Normal range (adults): 2.5 – 4.5 mg/dL

• Children and adolescents typically have higher normal values due to bone growth.

4. Interpreting Phosphorus Results

🔹 High Phosphorus (Hyperphosphatemia):

• May be due to chronic kidney disease, excessive phosphate intake, low parathyroid hormone (hypoparathyroidism), or tumor lysis syndrome.

• Can lead to calcium-phosphate deposits in tissues and vascular calcification.

🔹 Low Phosphorus (Hypophosphatemia):

• May result from malnutrition, vitamin D deficiency, hyperparathyroidism, alcoholism, or refeeding syndrome.

• Severe deficiency can cause muscle weakness, confusion, and bone pain.

5. What Can Affect Phosphorus Levels?

• Kidney function (major regulator of phosphorus excretion)

• Vitamin D and PTH levels

• Dietary intake of phosphate (e.g., processed foods, dairy, meats)

• Medications (e.g., antacids, diuretics, phosphate binders)

6. How Is the Test Performed?

• A blood sample is drawn from a vein.

• Fasting may be recommended, depending on provider instructions.

7. When to See a Doctor

🚨 Contact your healthcare provider if you:

• Have kidney disease or symptoms of phosphorus imbalance (e.g., muscle cramps, bone pain, fatigue).

• Are on dialysis or medications affecting phosphate balance.

• Experience unexplained calcium or vitamin D abnormalities.

🔹 Key Takeaways

✅ Phosphorus is a key mineral for bones, energy, and cellular function.

✅ Abnormal levels may signal kidney issues, nutritional imbalances, or hormonal disorders.

✅ Regular monitoring is important in people with chronic illness or electrolyte disturbances.

Potassium

The Potassium test measures the concentration of potassium in the blood. Potassium is a vital electrolyte that helps regulate heart function, nerve signals, and muscle contractions. Maintaining the proper balance of potassium is crucial for normal cellular and organ function, especially the heart and muscles.

1. What Is Potassium?

• Potassium is a positively charged electrolyte found primarily inside body cells.

• It plays an essential role in maintaining fluid balance, transmitting nerve impulses, and enabling muscle contraction.

• The kidneys help regulate potassium levels by excreting excess potassium in urine.

2. Why Is the Potassium Test Performed?

This test is used to:

• Detect electrolyte imbalances, especially in patients with kidney disease, heart issues, or on certain medications.

• Monitor potassium levels in patients receiving diuretics or potassium supplements.

• Help diagnose the cause of abnormal heart rhythms, weakness, or fatigue.

• Evaluate acid-base balance and adrenal gland function.

3. Potassium Reference Range

• Normal range (adults): 3.5 – 5.1 mmol/L (millimoles per liter)

• Values may vary slightly between labs.

4. Interpreting Potassium Results

🔹 High Potassium (Hyperkalemia):

• May result from kidney failure, Addison’s disease, potassium-sparing diuretics, or excessive potassium intake.

• Can cause irregular heartbeat, weakness, or cardiac arrest if severe.

🔹 Low Potassium (Hypokalemia):

• May be caused by diuretics, vomiting, diarrhea, eating disorders, or hyperaldosteronism.

• Can lead to muscle cramps, fatigue, constipation, or abnormal heart rhythms.

5. What Can Affect Potassium Levels?

• Kidney function and adrenal hormone activity

• Acid-base balance (e.g., acidosis or alkalosis)

• Medications (e.g., diuretics, ACE inhibitors, steroids)

• Diet (especially low or high potassium foods and supplements)

6. How Is the Test Performed?

• A blood sample is drawn from a vein.

• No special preparation is usually needed unless ordered as part of a metabolic panel.

7. When to See a Doctor

🚨 Contact your healthcare provider if you:

• Have symptoms of potassium imbalance (e.g., muscle weakness, palpitations, fatigue).

• Have kidney disease, heart problems, or are taking medications that affect potassium.

• Experience abnormal potassium levels on routine testing.

🔹 Key Takeaways

✅ Potassium is critical for heart, nerve, and muscle function.

✅ Both high and low levels can lead to serious health complications.

✅ Regular monitoring helps maintain safe electrolyte balance, especially in at-risk individuals.

Prealbumin (Thyroxine Binding Prealbumin / Transthyretin)

The Prealbumin test, also known as Transthyretin or Thyroxine Binding Prealbumin, measures the level of prealbumin in the blood. Prealbumin is a protein produced primarily by the liver and plays a role in transporting thyroid hormones (particularly thyroxine) and vitamin A. This test is often used to evaluate nutritional status and monitor protein-calorie malnutrition.

1. What Is Prealbumin?

• Prealbumin is a transport protein that binds and carries thyroxine (T4) and retinol-binding protein (which carries vitamin A).

• It has a short half-life (2–3 days), making it a sensitive marker for recent nutritional changes.

• Although its name suggests a relation to albumin, it is a distinct protein with different functions.

2. Why Is the Prealbumin Test Performed?

This test is used to:

• Evaluate nutritional status, especially in hospitalized patients or those receiving tube or IV feeding.

• Monitor response to nutritional therapy in malnourished individuals.

• Assess liver function or detect liver damage.

• Help differentiate causes of low serum protein levels.

3. Prealbumin Reference Range

• Normal range: 15 – 36 mg/dL (may vary by lab)

• Lower levels may indicate malnutrition or liver disease.

• Higher levels are less common but may be seen in certain inflammatory or renal conditions.

4. Interpreting Prealbumin Results

🔹 Low Prealbumin:

• Suggests protein-calorie malnutrition or inadequate intake.

• Can also be due to liver disease, inflammation, burns, or trauma.

🔹 High Prealbumin:

• May be seen in chronic kidney disease, steroid use, or dehydration.

• Less commonly used to diagnose disease than low values.

5. What Can Affect Prealbumin Levels?

• Recent dietary intake or nutritional supplementation

• Liver function (prealbumin is synthesized in the liver)

• Inflammatory states (prealbumin is a negative acute phase reactant)

• Kidney function and protein-losing conditions

6. How Is the Test Performed?

• A blood sample is drawn from a vein.

• No special preparation is required, but the test is often interpreted with other labs (e.g., CRP, albumin, liver panel).

7. When to See a Doctor

🚨 Contact your healthcare provider if you:

• Have symptoms of malnutrition, unexplained weight loss, or poor wound healing.

• Are being monitored for nutrition support or liver/kidney disease.

• Have abnormal prealbumin levels that require further evaluation.

🔹 Key Takeaways

✅ Prealbumin is a useful short-term marker for nutritional status and protein metabolism.

✅ Low levels may reflect malnutrition, liver dysfunction, or inflammation.

✅ Regular monitoring can help guide nutrition therapy and recovery in clinical settings.

ProBNP – N-terminal pro-B-type Natriuretic Peptide (NT-proBNP)

The NT-proBNP test measures the level of N-terminal pro-B-type natriuretic peptide in the blood. NT-proBNP is a non-active fragment released from the same molecule that produces BNP, a hormone secreted by the heart in response to stretching of heart muscle cells. This test is commonly used to help diagnose and monitor heart failure and other cardiac conditions.

1. What Is NT-proBNP?

• NT-proBNP is a byproduct released from the precursor molecule proBNP, which splits into BNP (active) and NT-proBNP (inactive).

• It is released when the heart is under strain, typically from volume overload or pressure buildup.

• NT-proBNP levels correlate with the severity of heart dysfunction, especially in congestive heart failure.

2. Why Is the NT-proBNP Test Performed?

This test is used to:

• Diagnose or rule out heart failure in patients with shortness of breath or fatigue.

• Evaluate the severity of heart failure and monitor treatment effectiveness.

• Assess prognosis in patients with known heart disease.

• Guide clinical decisions in emergency and outpatient settings.

3. NT-proBNP Reference Ranges (Age-dependent)

• < 50 years: < 450 pg/mL

• 50–75 years: < 900 pg/mL

• > 75 years: < 1800 pg/mL

• Heart failure likely if levels exceed these thresholds (based on age and symptoms).

• Lower thresholds (e.g., < 125 pg/mL) may be used in asymptomatic outpatient screening.

4. Interpreting NT-proBNP Results

🔹 Elevated NT-proBNP:

• Suggests heart failure or increased cardiac strain (e.g., valvular disease, atrial fibrillation).

• Levels correlate with severity of heart dysfunction.

• May also be elevated in renal failure, pulmonary hypertension, or advanced age.

🔹 Low NT-proBNP:

• Helps rule out heart failure as the cause of symptoms.

• Generally considered a good prognostic sign.

5. What Can Affect NT-proBNP Levels?

• Age (levels increase with age)

• Kidney function (reduced clearance in renal impairment)

• Obesity (may suppress NT-proBNP levels)

• Atrial fibrillation, pulmonary diseases, or anemia

6. How Is the Test Performed?

• A blood sample is drawn from a vein.

• No special preparation is required.

7. When to See a Doctor

🚨 Consult your healthcare provider if you:

• Have symptoms such as shortness of breath, swelling in the legs, or fatigue.

• Are being monitored for chronic heart failure or cardiac disease.

• Need help understanding test results or evaluating cardiac risk.

🔹 Key Takeaways

✅ NT-proBNP is a sensitive biomarker for diagnosing and managing heart failure.

✅ Elevated levels suggest cardiac strain or dysfunction and require further evaluation.

✅ The test helps guide treatment and monitor response in heart failure management.

Progesterone

The Progesterone test measures the level of the hormone progesterone in the blood. Progesterone is primarily produced in the ovaries after ovulation and plays a vital role in regulating the menstrual cycle, supporting pregnancy, and maintaining uterine lining. In men, progesterone is produced in small amounts and supports sperm development and other functions.

1. What Is Progesterone?

• Progesterone is a steroid hormone secreted mainly by the corpus luteum in the ovary after ovulation.

• It helps prepare the uterus for implantation of a fertilized egg and supports early pregnancy.

• In men, it is produced in smaller amounts by the adrenal glands and testes.

2. Why Is the Progesterone Test Performed?

This test is used to:

• Confirm ovulation in women trying to conceive.

• Monitor the health of a pregnancy (especially in early stages).

• Diagnose causes of infertility, abnormal uterine bleeding, or menstrual irregularities.

• Evaluate progesterone-producing tumors or adrenal gland disorders.

3. Progesterone Reference Ranges (Women)

• Follicular phase: < 1 ng/mL

• Luteal phase: 5 – 20 ng/mL

• First trimester pregnancy: 11 – 44 ng/mL

• Postmenopausal: < 1 ng/mL

• Men: < 1 ng/mL (varies by lab)

4. Interpreting Progesterone Results

🔹 High Progesterone:

• Indicates recent ovulation or pregnancy.

• May also be due to ovarian cysts, molar pregnancy, or certain hormone therapies.

🔹 Low Progesterone:

• Suggests lack of ovulation (anovulation), luteal phase deficiency, or risk of miscarriage.

• In men, low levels are rarely clinically significant unless related to adrenal or testicular dysfunction.

5. What Can Affect Progesterone Levels?

• Timing of the menstrual cycle (levels fluctuate significantly).

• Pregnancy status and trimester.

• Hormonal medications (e.g., birth control or fertility treatments).

• Medical conditions affecting ovulation or hormone production.

6. How Is the Test Performed?

• A blood sample is taken from a vein.

• Timing is important — usually done about 7 days after ovulation (day 21 of a 28-day cycle).

7. When to See a Doctor

🚨 Contact your healthcare provider if you:

• Are trying to conceive and want to confirm ovulation.

• Experience irregular periods, infertility, or abnormal bleeding.

• Have symptoms of low progesterone during pregnancy (e.g., spotting, cramping).

🔹 Key Takeaways

✅ Progesterone is essential for ovulation, fertility, and pregnancy maintenance.

✅ Low levels may affect the ability to conceive or carry a pregnancy.

✅ Accurate testing requires proper cycle timing and interpretation based on context.

Prolactin

The Prolactin test measures the level of prolactin hormone in the blood. Prolactin is produced by the pituitary gland and plays an important role in breast development and milk production during and after pregnancy. It also affects reproductive health in both women and men.

1. What Is Prolactin?

• Prolactin is a hormone secreted by the anterior pituitary gland.

• In women, it promotes breast development and stimulates milk production (lactation).

• In men and non-lactating women, prolactin has less defined roles but helps regulate reproductive hormones.

2. Why Is the Prolactin Test Performed?

This test is used to:

• Investigate menstrual irregularities or infertility in women.

• Diagnose the cause of galactorrhea (unexpected milk production).

• Evaluate decreased libido, erectile dysfunction, or infertility in men.

• Detect and monitor prolactin-secreting pituitary tumors (prolactinomas).

• Assess pituitary gland function.

3. Prolactin Reference Ranges

• Women (non-pregnant): 4.8 – 23.3 ng/mL

• Women (pregnant): up to 200 ng/mL or more

• Men: 4.0 – 15.2 ng/mL

• Reference ranges may vary slightly by lab.

4. Interpreting Prolactin Results

🔹 High Prolactin (Hyperprolactinemia):

• May be caused by prolactinoma (pituitary tumor), hypothyroidism, stress, or certain medications (e.g., antipsychotics, antidepressants).

• Can lead to irregular periods, infertility, breast milk production in non-pregnant women, and sexual dysfunction in men.

🔹 Low Prolactin:

• Less common and may be related to pituitary dysfunction.

• Could affect lactation in postpartum women.

5. What Can Affect Prolactin Levels?

• Physical or emotional stress

• Sleep, exercise, or recent meals (best measured in the morning after rest)

• Medications (e.g., antipsychotics, estrogen, opiates)

• Pituitary tumors or head trauma

6. How Is the Test Performed?

• A blood sample is drawn, typically in the morning after resting.

• Fasting is not always required, but some providers may recommend it.

7. When to See a Doctor

🚨 Contact your healthcare provider if you:

• Have symptoms like unexpected lactation, missed periods, infertility, or vision problems.

• Are being evaluated for pituitary or hormonal disorders.

• Have a known pituitary tumor and need regular monitoring.

🔹 Key Takeaways

✅ Prolactin is a key hormone for reproductive health and lactation.

✅ Elevated levels may indicate pituitary tumors or hormonal imbalances.

✅ Proper testing and interpretation can help diagnose treatable causes of infertility and other endocrine issues.

This test only measures Total PSA. Free PSA is not included.

Free PSA; Total PSA and % Free PSA

PSA (Prostate-Specific Antigen) is a protein produced by the prostate gland. The PSA test measures the level of this protein in the blood and is primarily used to screen for or monitor prostate disorders, including prostate cancer, benign prostatic hyperplasia (BPH), and prostatitis. This test panel includes total PSA, free PSA, and the ratio of free to total PSA (% Free PSA).

1. What Are Free PSA, Total PSA, and % Free PSA?

• Total PSA: The total amount of PSA in the bloodstream (both free and bound to proteins).

• Free PSA: The fraction of PSA not bound to blood proteins, freely circulating in the blood.

• % Free PSA: The ratio of free PSA to total PSA, calculated as: (Free PSA / Total PSA) × 100.

💡 Why measure % Free PSA?
This ratio helps distinguish between benign prostate conditions and prostate cancer, especially when total PSA is moderately elevated (between 4–10 ng/mL).

2. Why Is the PSA Test Panel Done?

This panel is used to:

• Screen for prostate cancer in men, especially those over 50 or at high risk.

• Investigate symptoms such as difficulty urinating, frequent urination, or pelvic pain.

• Monitor men with a history of prostate cancer or elevated PSA levels.

• Determine whether a prostate biopsy is necessary based on PSA results.

3. PSA Test Reference Ranges

• Total PSA:

  - < 4.0 ng/mL: Generally considered normal

  - 4.0 – 10.0 ng/mL: Borderline ('gray zone'); may require % Free PSA analysis

  - > 10.0 ng/mL: Higher likelihood of prostate cancer

• % Free PSA:

  - > 25%: Low risk of prostate cancer

  - 10–25%: Intermediate risk

  - < 10%: High risk of prostate cancer; further evaluation recommended

4. How to Interpret Free PSA, Total PSA, and % Free PSA

🔹 Low Total PSA (< 4.0 ng/mL): Usually no cause for concern, but trends over time matter.

🔹 Moderate PSA (4–10 ng/mL) with High % Free PSA (> 25%): Suggests benign conditions like BPH.

🔹 Moderate PSA (4–10 ng/mL) with Low % Free PSA (< 10%): Suggests a higher chance of prostate cancer; biopsy may be considered.

🔹 High PSA (> 10 ng/mL): High risk of prostate cancer or significant prostate inflammation/enlargement.

5. What Affects PSA Levels?

🔹 Factors that can increase PSA:

• Prostate cancer

• Benign prostatic hyperplasia (BPH)

• Prostatitis (inflammation of the prostate)

• Recent ejaculation or vigorous exercise (e.g., cycling)

• Prostate manipulation (e.g., digital rectal exam, catheterization)

🔹 Factors that can lower PSA:

• Certain medications (e.g., finasteride, dutasteride)

• Obesity

6. When to See a Doctor

🚨 Consult a healthcare provider if you:

• Have an elevated or rising PSA level

• Have a low % Free PSA with borderline total PSA

• Experience urinary symptoms or pelvic pain

• Have a family history of prostate cancer

🔹 Key Takeaways

✅ Total PSA measures all circulating PSA, while Free PSA measures the unbound portion.

✅ % Free PSA helps distinguish between prostate cancer and benign conditions.

✅ A low % Free PSA suggests higher cancer risk and may require further investigation.

This test measures Total PSA, and then measures Free PSA only if your total PSA is too high.

Free PSA; Total PSA and % Free PSA

PSA (Prostate-Specific Antigen) is a protein produced by the prostate gland. The PSA test measures the level of this protein in the blood and is primarily used to screen for or monitor prostate disorders, including prostate cancer, benign prostatic hyperplasia (BPH), and prostatitis. This test panel includes total PSA, free PSA, and the ratio of free to total PSA (% Free PSA).

1. What Are Free PSA, Total PSA, and % Free PSA?

• Total PSA: The total amount of PSA in the bloodstream (both free and bound to proteins).

• Free PSA: The fraction of PSA not bound to blood proteins, freely circulating in the blood.

• % Free PSA: The ratio of free PSA to total PSA, calculated as: (Free PSA / Total PSA) × 100.

💡 Why measure % Free PSA?
This ratio helps distinguish between benign prostate conditions and prostate cancer, especially when total PSA is moderately elevated (between 4–10 ng/mL).

2. Why Is the PSA Test Panel Done?

This panel is used to:

• Screen for prostate cancer in men, especially those over 50 or at high risk.

• Investigate symptoms such as difficulty urinating, frequent urination, or pelvic pain.

• Monitor men with a history of prostate cancer or elevated PSA levels.

• Determine whether a prostate biopsy is necessary based on PSA results.

3. PSA Test Reference Ranges

• Total PSA:

  - < 4.0 ng/mL: Generally considered normal

  - 4.0 – 10.0 ng/mL: Borderline ('gray zone'); may require % Free PSA analysis

  - > 10.0 ng/mL: Higher likelihood of prostate cancer

• % Free PSA:

  - > 25%: Low risk of prostate cancer

  - 10–25%: Intermediate risk

  - < 10%: High risk of prostate cancer; further evaluation recommended

4. How to Interpret Free PSA, Total PSA, and % Free PSA

🔹 Low Total PSA (< 4.0 ng/mL): Usually no cause for concern, but trends over time matter.

🔹 Moderate PSA (4–10 ng/mL) with High % Free PSA (> 25%): Suggests benign conditions like BPH.

🔹 Moderate PSA (4–10 ng/mL) with Low % Free PSA (< 10%): Suggests a higher chance of prostate cancer; biopsy may be considered.

🔹 High PSA (> 10 ng/mL): High risk of prostate cancer or significant prostate inflammation/enlargement.

5. What Affects PSA Levels?

🔹 Factors that can increase PSA:

• Prostate cancer

• Benign prostatic hyperplasia (BPH)

• Prostatitis (inflammation of the prostate)

• Recent ejaculation or vigorous exercise (e.g., cycling)

• Prostate manipulation (e.g., digital rectal exam, catheterization)

🔹 Factors that can lower PSA:

• Certain medications (e.g., finasteride, dutasteride)

• Obesity

6. When to See a Doctor

🚨 Consult a healthcare provider if you:

• Have an elevated or rising PSA level

• Have a low % Free PSA with borderline total PSA

• Experience urinary symptoms or pelvic pain

• Have a family history of prostate cancer

🔹 Key Takeaways

✅ Total PSA measures all circulating PSA, while Free PSA measures the unbound portion.

✅ % Free PSA helps distinguish between prostate cancer and benign conditions.

✅ A low % Free PSA suggests higher cancer risk and may require further investigation.

RPR Test – Rapid Plasma Reagin

The Rapid Plasma Reagin (RPR) test is a blood screening test used to detect syphilis, a sexually transmitted infection caused by the bacterium Treponema pallidum. RPR is a non-treponemal test that detects antibodies (reagin) produced in response to cellular damage from syphilis infection. It is commonly used for initial screening and for monitoring treatment effectiveness.

1. What Is the RPR Test?

• RPR is a non-specific test that detects reagin antibodies, which are not directed against the bacterium itself but against substances released by cells damaged by the infection.

• It is often used in combination with a specific treponemal test (e.g., FTA-ABS or TPPA) to confirm syphilis diagnosis.

2. Why Is the RPR Test Performed?

This test is used to:

• Screen for syphilis in individuals with symptoms or at risk of infection.

• Monitor response to syphilis treatment (a falling titer indicates successful therapy).

• Screen pregnant women, blood donors, or individuals with other sexually transmitted infections (STIs).

3. Interpreting RPR Results

🔹 Reactive (Positive) RPR:

• Suggests possible syphilis infection.

• Requires confirmation with a treponemal-specific test to confirm diagnosis.

• The test result is usually reported as a titer (e.g., 1:8, 1:64), which can be tracked over time to assess treatment response.

🔹 Non-reactive (Negative) RPR:

• Indicates no evidence of current syphilis infection.

• Early or late-stage syphilis may yield false-negative results — further testing may be needed if clinical suspicion is high.

4. What Can Affect RPR Test Accuracy?

• False positives may occur with pregnancy, autoimmune disorders (e.g., lupus), certain viral infections, or drug use.

• False negatives may occur in early syphilis, late syphilis, or due to the prozone effect (excess antibodies).

5. How Is the Test Performed?

• A blood sample is drawn from a vein.

• The test is typically performed in a lab or clinical setting with results available within hours to a few days.

6. When to See a Doctor

🚨 Consult your healthcare provider if you:

• Have had unprotected sex or exposure to a partner with syphilis.

• Experience symptoms such as sores, rash, or swollen lymph nodes.

• Are pregnant or planning pregnancy and need STI screening.

🔹 Key Takeaways

✅ The RPR test is a widely used screening tool for syphilis.

✅ Positive results require confirmation with specific treponemal tests.

✅ RPR titers are useful for diagnosing and monitoring treatment of syphilis.

Rheumatoid Factor (RF)

The Rheumatoid Factor (RF) test measures the level of RF antibodies in the blood. RF is an autoantibody that can target the body’s own tissues, and its presence is often associated with autoimmune diseases, particularly rheumatoid arthritis (RA). While RF is a key marker for RA, it may also be elevated in other conditions or even in healthy individuals.

1. What Is Rheumatoid Factor?

• RF is an antibody produced by the immune system that mistakenly targets the body’s own immunoglobulin G (IgG) antibodies.

• It is most commonly associated with autoimmune diseases such as rheumatoid arthritis and Sjögren's syndrome.

• The RF test measures the quantity of this antibody in the blood.

2. Why Is the RF Test Performed?

This test is used to:

• Help diagnose rheumatoid arthritis, especially in individuals with joint pain and inflammation.

• Support the diagnosis of other autoimmune diseases, such as Sjögren’s syndrome or mixed connective tissue disease.

• Monitor disease activity or treatment response in patients with RA.

3. RF Reference Range

• Normal: < 14 IU/mL (international units per milliliter)

• Values above the reference range are considered positive.

• Reference ranges may vary slightly between laboratories.

4. Interpreting RF Results

🔹 Positive RF:

• May support a diagnosis of rheumatoid arthritis, especially if symptoms are present.

• May also occur in other conditions: Sjögren’s syndrome, lupus, chronic infections (e.g., hepatitis, tuberculosis), or even in healthy older adults.

• Higher RF levels are more strongly associated with RA severity.

🔹 Negative RF:

• Does not rule out RA (seronegative RA is possible).

• May indicate a different form of arthritis or musculoskeletal condition.

5. What Can Affect RF Levels?

• Age (mild elevations are more common in elderly individuals)

• Chronic infections or liver disease

• Other autoimmune or inflammatory conditions

• Certain medications or recent vaccinations (rare)

6. How Is the Test Performed?

• A blood sample is drawn from a vein.

• No fasting or special preparation is typically required.

7. When to See a Doctor

🚨 Contact your healthcare provider if you:

• Experience persistent joint pain, stiffness, swelling, or fatigue.

• Have a positive RF test and need further evaluation for autoimmune disease.

• Are being monitored for known rheumatoid arthritis or similar conditions.

🔹 Key Takeaways

✅ RF is a common marker used in diagnosing rheumatoid arthritis and related autoimmune diseases.

✅ A positive result supports, but does not confirm, an autoimmune diagnosis.

✅ RF results must be interpreted in combination with symptoms, other lab tests (e.g., anti-CCP), and clinical findings.

Selenium Blood Test

The Selenium blood test measures the concentration of selenium in the blood. Selenium is an essential trace mineral important for antioxidant defense, thyroid function, DNA synthesis, and immune health. Both selenium deficiency and toxicity can have significant health consequences.

1. What Is Selenium?

• Selenium is a trace element that supports several selenoproteins involved in antioxidant protection and metabolic processes.

• It plays a crucial role in the production of glutathione peroxidase, an enzyme that protects cells from oxidative damage.

• Selenium is also vital for proper thyroid hormone metabolism and immune response.

2. Why Is the Selenium Test Performed?

This test is used to:

• Evaluate selenium status in individuals with signs of deficiency or excess.

• Monitor nutritional levels in patients on long-term parenteral nutrition.

• Investigate unexplained fatigue, weakened immunity, or thyroid dysfunction.

• Monitor selenium supplementation in at-risk populations.

3. Selenium Reference Range

• Normal serum selenium levels: 70 – 150 µg/L (micrograms per liter)

• Optimal levels can vary slightly by laboratory and testing method.

4. Interpreting Selenium Test Results

🔹 Low Selenium:

• May result from inadequate dietary intake, malabsorption disorders, or long-term critical illness.

• Associated with impaired immune function, hypothyroidism, infertility, and increased oxidative stress.

🔹 High Selenium:

• May result from excessive supplementation or environmental exposure.

• Symptoms of toxicity include hair loss, brittle nails, garlic breath odor, fatigue, and in severe cases, neurological damage.

5. What Can Affect Selenium Levels?

• Dietary intake (foods like Brazil nuts, seafood, meats, and grains)

• Soil selenium content in different geographic regions

• Use of selenium supplements or multivitamins

• Gastrointestinal absorption issues (e.g., celiac or Crohn’s disease)

6. How Is the Test Performed?

• A blood sample is collected from a vein, typically using trace-element-free tubes.

• No fasting is required unless ordered alongside other tests.

7. When to See a Doctor

🚨 Contact your healthcare provider if you:

• Experience symptoms of selenium deficiency or toxicity.

• Have a condition affecting nutrient absorption.

• Are taking selenium supplements and want to monitor your levels.

🔹 Key Takeaways

✅ Selenium is essential for antioxidant activity, thyroid health, and immune defense.

✅ Both low and high levels can impact health; blood testing can ensure optimal balance.

✅ A balanced diet with selenium-rich foods typically provides adequate levels.

Sex Hormone Binding Globulin (SHBG)

The Sex Hormone Binding Globulin (SHBG) test measures the amount of SHBG in the blood. SHBG is a protein produced by the liver that binds to sex hormones—primarily testosterone and estrogen—and regulates their bioavailability. This test is often used in evaluating hormonal imbalances, particularly related to testosterone in both men and women.

1. What Is SHBG?

• SHBG is a glycoprotein that binds tightly to sex hormones such as testosterone and estrogen.

• It controls how much of these hormones are freely available to tissues (free vs. bound hormone).

• Only unbound (free) hormones are biologically active, so SHBG levels affect overall hormone activity.

2. Why Is the SHBG Test Performed?

This test is used to:

• Evaluate symptoms of hormone imbalance (e.g., fatigue, infertility, low libido, irregular periods).

• Diagnose conditions such as polycystic ovary syndrome (PCOS), androgen deficiency, or estrogen excess.

• Help determine free testosterone levels when total testosterone results are inconclusive.

• Monitor liver function, as SHBG is produced in the liver.

3. SHBG Reference Ranges

• Men: 10 – 57 nmol/L

• Women: 18 – 144 nmol/L

• Levels vary depending on age, sex, liver function, and hormone status.

4. Interpreting SHBG Results

🔹 High SHBG:

• May result in lower free testosterone levels (even if total testosterone is normal).

• Common in hyperthyroidism, liver disease, estrogen therapy, and anorexia.

🔹 Low SHBG:

• May lead to higher free testosterone levels.

• Seen in insulin resistance, obesity, PCOS, hypothyroidism, and androgen use.

5. What Can Affect SHBG Levels?

• Liver health and function

• Thyroid status (high in hyperthyroidism, low in hypothyroidism)

• Hormonal therapies (e.g., estrogen or testosterone supplementation)

• Metabolic disorders such as obesity, diabetes, or PCOS

6. How Is the Test Performed?

• A blood sample is taken from a vein.

• Fasting may or may not be required—follow your provider's instructions.

7. When to See a Doctor

🚨 Speak with your healthcare provider if you:

• Have symptoms of low testosterone or estrogen imbalance.

• Experience unexplained infertility, weight changes, or changes in sexual function.

• Have abnormal hormone levels and need a deeper evaluation.

🔹 Key Takeaways

✅ SHBG controls the amount of active sex hormones in the body.

✅ Abnormal levels can disrupt hormone balance and reproductive function.

✅ SHBG testing helps provide a clearer picture when hormone-related symptoms are present.

Sodium

The Sodium test measures the level of sodium in the blood. Sodium is a vital electrolyte that helps regulate fluid balance, blood pressure, nerve function, and muscle contraction. Maintaining proper sodium levels is essential for normal cellular function and overall health.

1. What Is Sodium?

• Sodium is an essential electrolyte and mineral found in the blood and body fluids.

• It helps control fluid balance, transmit nerve signals, and support proper muscle function.

• The kidneys help regulate sodium levels by adjusting how much is excreted in urine.

2. Why Is the Sodium Test Performed?

This test is used to:

• Evaluate fluid and electrolyte balance.

• Diagnose causes of symptoms like weakness, confusion, dehydration, or swelling.

• Monitor chronic conditions such as kidney disease, heart failure, or adrenal disorders.

• Check for imbalances in people receiving IV fluids, diuretics, or other medications.

3. Sodium Reference Range

• Normal range: 135 – 145 mmol/L

• Values may vary slightly depending on the laboratory and patient’s condition.

4. Interpreting Sodium Results

🔹 High Sodium (Hypernatremia):

• May indicate dehydration, excessive salt intake, kidney disease, or certain endocrine disorders.

• Can cause symptoms such as thirst, confusion, muscle twitching, or seizures in severe cases.

🔹 Low Sodium (Hyponatremia):

• May result from fluid overload, heart failure, kidney or liver disease, or use of diuretics.

• Can cause headache, nausea, confusion, seizures, and even coma if severe.

5. What Can Affect Sodium Levels?

• Hydration status (dehydration or overhydration)

• Kidney function and water regulation

• Medications such as diuretics, antidepressants, or antiepileptics

• Hormonal conditions (e.g., SIADH, Addison's disease, Cushing’s syndrome)

6. How Is the Test Performed?

• A blood sample is drawn from a vein.

• Sodium is often measured as part of a basic or comprehensive metabolic panel.

7. When to See a Doctor

🚨 Contact your healthcare provider if you:

• Experience symptoms such as confusion, swelling, weakness, or fatigue.

• Have conditions that affect sodium levels or are taking medications that impact electrolyte balance.

• Receive abnormal results and need further evaluation.

🔹 Key Takeaways

✅ Sodium is crucial for hydration, nerve, and muscle function.

✅ Imbalances can lead to serious health issues, especially affecting the brain and heart.

✅ Monitoring is important for patients with kidney disease, on certain medications, or with fluid balance concerns.