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Understand the 1-mg low-dose dexamethasone suppression test, the common cortisol cutoff of 1.8 mcg/dL, causes of nonsuppression, and the follow-up used for Cushing screening.

Low-Dose Dexamethasone Suppression Test: Cushing Syndrome Screening and Results

Learn how an 8–9 a.m. cortisol test screens for adrenal insufficiency, what low and intermediate results mean, how ACTH helps identify the cause, and when stimulation testing is needed.

Morning Cortisol Test: Low Levels, Adrenal Insufficiency, and Results

Learn how a pheochromocytoma and paraganglioma panel uses plasma or urine metanephrines, normetanephrine, catecholamines, and controlled collection to interpret abnormal results.

Pheochromocytoma and Paraganglioma Test Panel: Metanephrines, Normetanephrine, Catecholamines, and Results

Learn what plasma epinephrine, norepinephrine, and dopamine results mean, why collection posture matters, common causes of high values, and when metanephrine testing is preferred.

Plasma Catecholamines Test: Epinephrine, Norepinephrine, Dopamine, and Results

Learn how plasma free metanephrine and normetanephrine testing screens for pheochromocytoma and paraganglioma, why supine rest matters, and how high or borderline results are evaluated.

Plasma Free Metanephrines Test: Pheochromocytoma and Paraganglioma Screening, High Levels, and Results

Learn what a high plasma normetanephrine result means, why supine rest matters, common false-positive causes, when clonidine testing is used, and how PPGL evaluation proceeds.

Plasma Normetanephrine Test: High Levels, Pheochromocytoma Screening, and Results

Diagnostics

Home Diagnostics Page 38

Learn the normal transferrin saturation range, what low or high TSAT means, how it is calculated, and how TSAT fits with ferritin, serum iron, TIBC, and anemia testing.

Transferrin Saturation (TSAT) Normal Range: Reference Values and Meaning

Learn what the UIBC blood test measures, the common normal range, and how high or low UIBC results relate to iron deficiency, iron overload, ferritin, TIBC, and transferrin saturation.

Unsaturated Iron-Binding Capacity (UIBC) Test Normal Range: Reference Values and Meaning

Learn what a vitamin A retinol blood test measures, common normal ranges, low and high result meanings, deficiency cutoffs, toxicity concerns, preparation tips, and follow-up tests.

Vitamin A (Retinol) Test Normal Range: Reference Values and Meaning

Learn what a vitamin and mineral blood test panel measures, how to interpret low or high nutrient levels, which markers matter, and when follow-up testing is needed.

Vitamin and Mineral Blood Test Panel: Deficiency, Toxicity, Nutrient Levels, and...

Learn what a vitamin B1 thiamine test measures, common normal ranges, low and high result meanings, deficiency symptoms, causes, preparation, and follow-up steps.

Vitamin B1 (Thiamine) Test: Low Thiamine, Deficiency, Normal Range, and Results

Learn what a vitamin B2 riboflavin test measures, normal ranges for plasma, whole blood, and EGRAC, causes of low riboflavin, deficiency symptoms, and follow-up testing.

Vitamin B2 (Riboflavin) Test: Low Riboflavin, Deficiency, Normal Range, and Results

Learn what a vitamin B3 niacin test measures, what low or high results mean, common normal ranges, deficiency symptoms, pellagra risk, test preparation, and safe follow-up.

Vitamin B3 (Niacin) Test: Low Niacin, Deficiency, Normal Range, and Results

Learn what a vitamin B5 blood test measures, what low pantothenic acid may mean, how normal ranges vary, and how to interpret deficiency or high results.

Vitamin B5 (Pantothenic Acid) Test: Low Pantothenic Acid, Deficiency, Normal Range,...

Understand the vitamin B6 PLP blood test normal range, low and high results, symptoms, causes, supplement risks, preparation tips, and follow-up testing.

Vitamin B6 (Pyridoxal-5-Phosphate/PLP) Test Normal Range: Reference Values and Meaning

Learn what a vitamin B7 biotin test measures, normal range examples, causes of low biotin, deficiency symptoms, high supplement levels, lab interference, and follow-up testing.

Vitamin B7 (Biotin) Test: Low Biotin, Deficiency, Normal Range, and Results

Learn how vitamin B12 and MMA results are interpreted together, what high MMA can mean, when supplements help, and how to avoid overdoing B12 replacement.

Vitamin B12 and MMA: Interpreting B12 Status Without Overdoing Supplements

Understand the vitamin B12 blood test normal range, low and high B12 results, borderline values, symptoms, causes, and follow-up tests like MMA and homocysteine.

Vitamin B12 Blood Test Normal Range: Reference Values and Meaning

Learn how vitamin B12 and folate deficiencies differ, how CBC patterns, MMA, homocysteine, and folate tests help interpret macrocytic anemia, and when follow-up matters.

Vitamin B12 vs Folate: Interpreting Anemia and Nutrient Deficiency

Understand the vitamin C blood test, including normal range, low vitamin C, deficiency cutoffs, scurvy risk, symptoms, preparation, false results, and follow-up testing.

Vitamin C Blood Test: Low Vitamin C, Deficiency, Normal Range, Scurvy...

Learn how to interpret vitamin D, calcium, PTH, phosphorus, magnesium, and kidney-related blood tests, including low vitamin D patterns, high calcium causes, low calcium symptoms, and when follow-up matters.

Vitamin D and Calcium: Interpreting Bone and Mineral Blood Tests

Learn the difference between 25-hydroxy vitamin D and 1,25-dihydroxy vitamin D, including which test checks deficiency, when calcitriol testing is useful, and how calcium, PTH, and kidney function change interpretation.

Vitamin D vs 1,25-Dihydroxy Vitamin D: What Is the Difference?

Learn what a vitamin E alpha-tocopherol blood test measures, the normal adult range, causes of low or high results, preparation, follow-up tests, and supplement safety.

Vitamin E (Alpha-Tocopherol) Test Normal Range: Reference Values and Meaning

Learn what a vitamin K blood test measures, what low vitamin K means, how deficiency affects PT/INR and bleeding risk, and what abnormal results may need next.

Vitamin K Blood Test: Low Vitamin K, Deficiency, Bleeding Risk, and...

Learn what the vitamin K1 phylloquinone test measures, what low vitamin K1 means, common reference ranges, deficiency causes, preparation tips, and follow-up tests.

Vitamin K1 (Phylloquinone) Test: Low Vitamin K1, Normal Range, Deficiency, and...

Interpret zinc and copper blood tests with confidence, including normal ranges, deficiency and excess patterns, supplement risks, ceruloplasmin, diet, and when to follow up.

Zinc and Copper: Interpreting Mineral Balance Without Overdoing Supplements

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