Lp(a) is a genetically influenced lipoprotein that is being studied as an independent contributor to cardiovascular risk. Learn what the test measures, how thresholds are used, and where the evidence is still developing.
Learn when clinicians should order lipoprotein(a) testing, what Lp(a) levels mean, normal ranges, and evidence-based strategies for managing elevated Lp(a) cardiovascular risk.
Learn how your LP-IR score from NMR LipoProfile testing guides medication choices, lifestyle interventions, and metabolic treatment decisions for insulin resistance.
Learn what your LP-IR score really means, how standard lab ranges differ from functional optimal targets, and evidence-based strategies to improve NMR-derived insulin resistance markers.
Learn when clinicians should order the LP-IR score from NMR LipoProfile testing, what the results mean, how to interpret the 0, 100 scale, and which patients benefit most from this early insulin resistance marker.
RBC magnesium samples magnesium inside red blood cells, unlike serum. This page covers what the test measures and what evidence shows about treatment.
Sources reviewed here did not measure RBC magnesium. See the adult supplement upper limit, one form comparison, kidney risk and medicine spacing.
Learn what your RBC magnesium level means, how it differs from serum magnesium, the optimal range for tissue status, and evidence-based steps to correct a low or high result.
Beta-blockers, NSAIDs, caffeine, and other medications can raise or suppress salivary melatonin levels and complicate dim-light melatonin onset (DLMO) testing. A clinical guide to medication and behavioral interference, with a decision framework for deciding whether a result is trustworthy.
A salivary melatonin profile maps dim-light melatonin onset (DLMO) and secretion amplitude. This explains what the result can and cannot tell a clinician about timing sleep medication, light therapy, and melatonin supplementation.
Learn how to interpret your salivary melatonin profile results and use proven strategies including light timing, supplementation, and lifestyle changes to optimize melatonin output and circadian health.
Learn when clinicians order a salivary melatonin profile, what normal ranges look like, how to interpret high or low results, and which patients benefit most from circadian phase assessment.
How OGTT results at each threshold shift your prescriptions, monitoring schedule, and lifestyle plan for prediabetes, type 2 diabetes, and gestational diabetes.
The OGTT measures how efficiently your body clears a standardized glucose load over two hours. Learn normal ranges, what abnormal results mean, and when clinicians order this test.
It is unknown whether orlistat changes the Omega-3 Index. EPA and DHA dose, starting index and supplement form are what predict how far it moves.
A clinician-guided list of lab tests to pair with the Omega-3 Index for a complete cardiovascular, metabolic, and inflammatory risk picture.
Dozens of common medications raise or suppress serum prolactin, creating false signals for pituitary MRI. Learn which drugs distort the test, how to interpret results on medication, and when imaging is truly warranted.
Learn when prolactin or cortisol levels trigger a pituitary MRI, what the imaging reveals, and how findings shift your treatment from medication to monitoring or surgery.
Learn when a pituitary MRI is indicated, what the results mean for prolactin and cortisol levels, and evidence-based strategies to manage the underlying conditions that triggered imaging.
Evidence-based guide to pituitary MRI indications based on prolactin, cortisol, IGF-1, and other lab findings. Includes Endocrine Society thresholds, prolactinoma size correlation, and clinical decision criteria.
Prometrium's label gives fixed doses with no serum-level target. See what blood levels look like after an oral dose and the labeled contraindications.
TRT can raise prolactin, but levels above 25 ng/mL (women) or 20 ng/mL (men) trigger specific clinical steps, from monitoring to MRI to treatment changes.
A clinical guide to the prolactin blood test, including what it measures, normal ranges, causes of high and low levels, and how results guide treatment decisions.
Order a prolactin test for galactorrhea, menstrual changes, infertility, or ED. Draw fasting in the morning; over 25 ng/mL (women) or 20 ng/mL (men) needs follow-up.
A clinical guide to medications that artificially raise or lower PSA levels, including 5-alpha reductase inhibitors, testosterone, NSAIDs, statins, and thiazides. Know which drugs affect your PSA before screening.
Standard PRA range is 0.15 to 5.82 ng/mL/hr depending on posture; functional optimal target is 0.5 to 2.5 ng/mL/hr. See what your number means.
Plasma renin activity (PRA) measures the rate at which renin converts angiotensinogen to angiotensin I. Learn normal ranges, what high or low PRA means, and how clinicians use this test to evaluate hypertension, aldosteronism, and adrenal disorders.
Stimulants, anticholinergics, and high-dose levothyroxine can raise resting heart rate by 5 to 15 bpm or more. See which drugs skew your reading and by how much.
Learn what your resting heart rate means, what normal ranges look like by age and fitness level, when to worry about high or low readings, and evidence-based ways to improve your number.
60-100 bpm is normal, but studies tie lowest mortality risk to 50-70 bpm. See why 85 bpm raises risk 16-20% and what affects your number.
A clinician-guided breakdown of the lab tests you should pair with resting heart rate to uncover thyroid dysfunction, anemia, metabolic syndrome, and autonomic imbalance.
Your serum selenium level directly shapes thyroid medication dosing, antioxidant status, and supplementation decisions. Here is what each range means for your care plan.
How to raise or lower your selenium level with dietary changes, supplementation, and clinical monitoring. Includes normal ranges, food sources, and dosing backed by peer-reviewed research.
Learn how to read your selenium blood test, what normal ranges mean, and what high or low levels signal for thyroid function, antioxidant defense, and overall health.
Sex hormone-binding globulin (SHBG) shapes how much testosterone and estradiol actually reach your tissues. Learn how high or low SHBG levels change TRT, HRT, and metabolic prescribing decisions.
Learn how to read your SHBG (extended) lab result, what high and low levels mean for testosterone and estrogen balance, and when to act on abnormal values.
Learn the difference between standard lab-normal SHBG ranges and functional optimal levels, why it matters for hormone therapy, and how to interpret your results with total and free testosterone or estradiol.
A clinical guide to interpreting urinary sex steroid metabolites, including estrogen detox pathways (2-OH/16α-OH ratio), androgen metabolites, and the gap between standard reference ranges and functional optimal targets.
Understanding SHBG blood test results beyond standard lab ranges. Learn what functional optimal SHBG levels look like for hormonal health, how to interpret your results, and evidence-based strategies to modify SHBG.
Learn which lab tests to pair with SHBG for accurate hormone assessment, including total testosterone, free testosterone, estradiol, albumin, thyroid panel, and metabolic markers.
Learn what your SIBO breath test results mean and how hydrogen and methane patterns guide treatment choices, including rifaximin, elemental diets, and prokinetics.
SIBO testing measures hydrogen and methane after a sugar substrate. Learn when to order it, prep steps, washout times, and positive thresholds.
A clinical guide to the blood tests and biomarkers that often accompany a polysomnography sleep study, including thyroid, testosterone, metabolic, and iron panels, with notes on what is established versus what needs individual verification.
The Boston Heart sterol balance test classifies you as a cholesterol absorber or synthesizer. Learn how this result may inform statin, ezetimibe, and combination therapy discussions, and where the evidence is still limited.
Learn what your Boston Heart sterol balance result means, whether you are a cholesterol absorber or producer, and proven ways to improve your number with targeted therapy and diet.
The Boston Heart sterol balance test identifies whether you are a cholesterol absorber or producer. Learn what markers it measures, how to read your results, and why the distinction changes which lipid drug works best for you.
Learn when to order the Boston Heart Sterol Balance test, what absorber vs. producer phenotypes mean for statin and ezetimibe therapy, and how to interpret your results.
A guide to interpreting comprehensive stool analysis results, comparing conventional lab normals with functional optimal ranges for digestive markers, microbiome diversity, and inflammatory biomarkers.
A detailed breakdown of every marker in a comprehensive stool analysis, from digestive function and microbial balance to inflammation and immune activity, with clinical reference ranges and interpretation guidance.
Learn when clinicians order a comprehensive stool analysis, what the test measures, how to interpret results, and which symptoms and conditions warrant this diagnostic workup.
A guide to telomere length: what the test measures, normal ranges, and the lifestyle, pharmacologic, and supplemental interventions shown in peer-reviewed trials to preserve or lengthen telomeres.
Learn what your telomere length test result means, what normal ranges look like, and evidence-based strategies to maintain or improve telomere length over time.
Understand what your telomere length result means, how standard lab ranges compare to research-backed functional targets, and evidence-based strategies to protect telomere integrity over time.
Telomere length testing quantifies the protective DNA caps on your chromosomes. Learn what normal ranges look like, what short or long telomeres mean, and how to interpret your results.
Learn when telomere length testing is clinically useful, what results mean, normal ranges, and evidence-based strategies to protect telomere integrity over time.
Travison 2017 set the harmonized total testosterone reference range at 264-916 ng/dL, but many clinicians target 500-700 ng/dL for symptom relief.
A clinical guide to the lab panels you should order with total testosterone, including free testosterone, SHBG, LH, FSH, estradiol, CBC, and metabolic markers.
Total testosterone measures all testosterone in your blood, both protein-bound and free. Learn what the test captures, normal reference ranges by age and sex, and what high or low results mean for your health.
Learn when clinicians order a total testosterone blood test, what normal ranges look like, and how results guide treatment decisions for hypogonadism, PCOS, and hormone therapy.
Biotin, amiodarone, lithium, checkpoint inhibitors, and interferon-alpha can all distort TPO antibody results. Learn which medications raise, lower, or analytically falsify your TPO test.