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.

Syphilis Test

Syphilis testing detects infection with the bacterium *Treponema pallidum*, which causes syphilis—a sexually transmitted infection (STI) that can progress through multiple stages if untreated. Testing helps diagnose current or past infection and guide appropriate treatment. Syphilis tests include non-treponemal (e.g., RPR, VDRL) and treponemal (e.g., FTA-ABS, TPPA) assays.

1. What Is Syphilis?

• Syphilis is a bacterial STI transmitted through direct contact with syphilitic sores, usually during sexual activity or from mother to child during pregnancy (congenital syphilis).

• The disease has four stages: primary, secondary, latent, and tertiary, each with distinct symptoms and complications.

• Early detection and treatment prevent long-term damage and transmission.

2. Types of Syphilis Tests

🔹 Non-Treponemal Tests:

• RPR (Rapid Plasma Reagin) and VDRL (Venereal Disease Research Laboratory) tests detect non-specific antibodies (reagin).

• Used for screening and monitoring treatment (titers drop with successful therapy).

🔹 Treponemal Tests:

• FTA-ABS (Fluorescent Treponemal Antibody Absorption), TPPA (Treponema pallidum Particle Agglutination), or EIA (Enzyme Immunoassay).

• Detect specific antibodies to *T. pallidum* and remain positive for life, even after treatment.

3. Why Is the Syphilis Test Performed?

• Diagnose syphilis in symptomatic individuals (e.g., genital sores, rash, swollen lymph nodes).

• Screen high-risk populations (e.g., individuals with other STIs, sex workers, pregnant women, or men who have sex with men).

• Confirm syphilis after positive screening results.

• Monitor treatment response using non-treponemal titers.

4. Interpreting Test Results

🔹 Positive Non-Treponemal and Treponemal Tests:

• Indicates active or past syphilis infection.

• Requires clinical correlation and possibly additional staging tests.

🔹 Positive Treponemal Test and Negative Non-Treponemal Test:

• May indicate past treated syphilis or late/latent infection.

🔹 Negative Tests:

• Likely no current or past infection (note that early syphilis may yield false negatives).

5. What Can Affect Test Accuracy?

• False positives can occur in autoimmune diseases, pregnancy, HIV, or other infections.

• False negatives may happen in early syphilis, latent infection, or with the prozone effect.

• Diagnosis often requires a combination of tests and clinical history.

6. How Is the Test Performed?

• A blood sample is drawn from a vein.

• Sometimes, spinal fluid or lesion swabs are tested in advanced or congenital syphilis.

7. When to See a Doctor

🚨 Seek medical care if you:

• Have unexplained sores, rashes, or sexual exposure to syphilis.

• Are pregnant and have not been tested for syphilis.

• Need follow-up or treatment monitoring for a known diagnosis.

🔹 Key Takeaways

✅ Syphilis is a serious but curable STI if detected early.

✅ Testing involves both screening and confirmatory methods.

✅ Regular testing is important for at-risk individuals and prenatal care.

T3 (Triiodothyronine), Free

The Free T3 (Triiodothyronine) test measures the level of unbound, active T3 hormone circulating in the blood. Unlike Total T3, which includes both bound and free hormone, Free T3 provides a more accurate picture of the biologically active hormone available to tissues. This test is often used to assess thyroid function and diagnose hyperthyroidism.

1. What Is Free T3?

• Free T3 represents the small fraction of triiodothyronine not bound to proteins and available to act on cells.

• It plays a crucial role in regulating metabolism, energy use, and temperature control.

• Most of the T3 in the body is bound to carrier proteins and inactive, while Free T3 is active and functional.

2. Why Is the Free T3 Test Performed?

This test is used to:

• Evaluate thyroid function and detect hyperthyroidism.

• Investigate symptoms such as anxiety, weight loss, rapid heart rate, or heat intolerance.

• Help assess thyroid hormone status when TSH or Free T4 results are abnormal.

• Monitor thyroid treatment in patients on hormone therapy.

3. Free T3 Reference Range

• Normal range: 2.0 – 4.4 pg/mL (may vary slightly between labs)

• Interpretation should consider TSH and Free T4 levels for a complete thyroid profile.

4. Interpreting Free T3 Results

🔹 Elevated Free T3:

• Common in hyperthyroidism (e.g., Graves’ disease).

• May cause symptoms like nervousness, sweating, fast heart rate, or unexplained weight loss.

🔹 Low Free T3:

• May occur in hypothyroidism or in non-thyroidal illness (euthyroid sick syndrome).

• Can also occur in patients with pituitary or hypothalamic dysfunction.

5. What Can Affect Free T3 Levels?

• Thyroid medications (levothyroxine, liothyronine)

• Acute illness or stress (can temporarily suppress levels)

• Pregnancy or use of estrogen-containing medications

• Liver disease or changes in thyroid-binding proteins

6. How Is the Test Performed?

• A blood sample is taken from a vein.

• Fasting is not usually required unless specified by your provider.

7. When to See a Doctor

🚨 See a healthcare provider if you:

• Experience symptoms of thyroid dysfunction such as weight changes, fatigue, or heat/cold sensitivity.

• Are being treated for a thyroid condition and need monitoring.

• Have abnormal TSH or T4 results requiring further evaluation.

🔹 Key Takeaways

✅ Free T3 measures the active form of triiodothyronine circulating in your bloodstream.

✅ It is a key test in diagnosing and managing hyperthyroidism.

✅ Results should be interpreted along with TSH and Free T4 levels for accurate thyroid assessment.

T3 (Triiodothyronine), Total

The T3 (Triiodothyronine), Total test measures the total amount of triiodothyronine hormone in the blood, including both free (active) and bound (inactive) forms. T3 is one of the two main hormones produced by the thyroid gland and plays a critical role in regulating metabolism, heart rate, body temperature, and energy use.

1. What Is T3?

• T3 (triiodothyronine) is a thyroid hormone derived from T4 (thyroxine) and is the more biologically active form.

• Total T3 includes both free T3 (active) and T3 bound to proteins such as thyroxine-binding globulin (TBG).

• T3 levels help assess thyroid gland function and metabolism.

2. Why Is the Total T3 Test Performed?

This test is used to:

• Diagnose hyperthyroidism (overactive thyroid) or assess its severity.

• Help evaluate thyroid function when TSH and T4 results are abnormal or inconclusive.

• Monitor treatment for thyroid disorders.

• Investigate symptoms of thyroid dysfunction such as weight changes, fatigue, or anxiety.

3. T3 Total Reference Range

• Normal range: 80 – 200 ng/dL (may vary slightly by laboratory)

• Interpretation should be based on accompanying TSH and T4 levels.

4. Interpreting T3 Total Results

🔹 Elevated T3:

• Suggests hyperthyroidism (e.g., Graves’ disease, thyroid nodules).

• Can cause symptoms such as weight loss, rapid heartbeat, irritability, and heat intolerance.

🔹 Low T3:

• May indicate hypothyroidism or non-thyroidal illness (e.g., during acute illness or malnutrition).

• Low T3 may occur even when TSH and T4 are normal (low T3 syndrome).

5. What Can Affect T3 Levels?

• Protein-binding changes (e.g., liver disease, pregnancy, oral contraceptives)

• Certain medications (e.g., steroids, amiodarone, beta-blockers)

• Nutritional status and chronic illness

• Thyroid hormone replacement therapy

6. How Is the Test Performed?

• A blood sample is taken from a vein.

• Fasting is not typically required unless part of a broader panel.

7. When to See a Doctor

🚨 Contact your healthcare provider if you:

• Have symptoms of thyroid imbalance (e.g., fatigue, weight gain/loss, temperature sensitivity).

• Are being treated for thyroid disease and need monitoring.

• Have unexpected changes in metabolism, mood, or heart rate.

🔹 Key Takeaways

✅ Total T3 helps assess overall thyroid hormone status, especially in hyperthyroid conditions.

✅ Abnormal levels should be interpreted alongside TSH and T4.

✅ This test supports diagnosis and monitoring of thyroid dysfunction.

T4 (Thyroxine), Free

The Free T4 (Thyroxine) test measures the level of unbound T4 hormone circulating in the blood. Free T4 is the biologically active form of thyroxine, which plays a vital role in regulating metabolism, energy production, and overall cellular function. This test is frequently used alongside TSH testing to evaluate thyroid function.

1. What Is Free T4?

• Free T4 is the portion of total T4 that is not bound to proteins and is available to enter tissues and exert metabolic effects.

• It is the active form of the primary thyroid hormone produced by the thyroid gland.

• T4 is converted into T3 (triiodothyronine) in the body, which is even more metabolically active.

2. Why Is the Free T4 Test Performed?

This test is used to:

• Diagnose and monitor thyroid disorders, such as hypothyroidism and hyperthyroidism.

• Evaluate abnormal TSH levels or investigate symptoms of thyroid dysfunction.

• Monitor the effectiveness of thyroid replacement therapy.

• Assess thyroid function in people with pituitary or hypothalamic disease.

3. Free T4 Reference Range

• Normal range: 0.8 – 1.8 ng/dL (may vary slightly by lab)

• Interpretation depends on context and should be assessed alongside TSH levels.

4. Interpreting Free T4 Results

🔹 Elevated Free T4:

• Suggests hyperthyroidism or excessive thyroid hormone replacement.

• Common in Graves’ disease, thyroiditis, or overmedication with levothyroxine.

🔹 Low Free T4:

• Indicates hypothyroidism, especially when accompanied by elevated TSH.

• May also result from pituitary dysfunction (secondary hypothyroidism).

5. What Can Affect Free T4 Levels?

• Thyroid hormone medications or iodine supplements

• Liver and kidney function (affect hormone binding and clearance)

• Severe illness or stress (can temporarily affect hormone levels)

• Changes in thyroid-binding globulin levels due to estrogen or steroids

6. How Is the Test Performed?

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

• Fasting is typically not required unless ordered with other tests.

7. When to See a Doctor

🚨 Contact your healthcare provider if you:

• Experience fatigue, weight changes, depression, dry skin, or temperature sensitivity.

• Are taking thyroid hormone therapy and require regular monitoring.

• Have abnormal TSH results or a family history of thyroid disorders.

🔹 Key Takeaways

✅ Free T4 is the active form of thyroxine and is crucial for assessing thyroid function.

✅ It provides valuable insight when used with TSH and other thyroid tests.

✅ Monitoring Free T4 helps guide diagnosis and treatment of thyroid conditions.