Lab markers, read with the assay in mind
What a marker measures, what moves it, and why the method printed on your report changes the answer. Reference pages for the bloodwork people on hormone therapy and peptide protocols actually run.
The gap these pages fill
Search for a lab marker and you will find a range, a bolded "optimal" number and no mention of how the value was produced. That omission is the single most common way people misread their own bloodwork.
Sensitive (LC/MS-MS) estradiol and standard immunoassay estradiol are not the same measurement. Direct-immunoassay free testosterone, calculated free testosterone and equilibrium dialysis are three different answers to the same question. A ferritin drawn after a blood donation is telling you about the donation. TherapyLog stores the assay method as part of the result rather than throwing it away, and these pages are written the same way: whenever the method changes the interpretation, the page names it.
Three rules every page here follows
- Your lab's printed range wins. The reference interval on your own report belongs to the assay and the instrument that produced your number. Where a page shows a generic range, it is labelled generic — a fallback, not a correction of your report.
- Optimal bands are non-diagnostic. Where a page shows an optimal band drawn from clinical literature and community practice, it is there for reading a trend over time. It does not diagnose anything, and being outside one is not a finding.
- Interpretation ends with your clinician. These pages describe what the literature and community practice report, and show the basis for every number. They do not tell a reader with a particular result to take a particular drug at a particular dose.
Published
Each carries the accepted units and their conversions, the assay variants the app tracks, the generic range, the non-diagnostic optimal band where one exists, the sex and age bands generated from the app's own range function, a unit converter running the app's own conversion code, and cited sources.
Sensitive versus standard estradiol
Standard estradiol immunoassays are unreliable at male concentrations. What the sensitive and LC/MS-MS methods measure, and how to read one.
Total testosterone
Why two labs report different total testosterone from the same blood, what the range does with age, and how to read an unstated method.
Free versus total testosterone, and the three ways labs get the free number
Calculated, direct immunoassay and equilibrium dialysis free testosterone are three measurements. Why they disagree, and where SHBG comes in.
SHBG
SHBG decides how much of your testosterone is available. What raises and lowers it, why high SHBG on TRT is a common complaint, how to read it.
Hematocrit on testosterone therapy
Testosterone raises hematocrit. What the guideline thresholds are, why draw conditions matter, and what routine donation trades away.
Prolactin
Prolactin is easy to elevate by accident and easy to over-treat. What raises it, why a single high value gets repeated, and how units differ.
LH and FSH
LH and FSH show whether your own production is running. What they do on testosterone therapy, what recovery looks like, and why timing decides.
IGF-1
IGF-1 cannot be read without an age. What the age bands are, why assay standardisation matters, and what growth hormone secretagogues actually move.
HbA1c and fasting glucose
How mmol/mol converts to percent, what fasting glucose and insulin add, and why anything shortening red cell lifespan biases HbA1c low.
ApoB versus LDL cholesterol
LDL-C measures cholesterol carried; ApoB counts the particles carrying it. Why they disagree, and which LDL calculation your lab used.
Lipoprotein(a)
Lp(a) is reported in nmol/L or mg/dL and the two are not interconvertible. Why the 2.5 factor is wrong, what the assay does, and what one number is for.
Ferritin and the iron panel on TRT
Testosterone lowers ferritin before you ever donate. How to read ferritin, iron, TIBC, transferrin and saturation together as one panel.
Vitamin D (25-OH-D)
Vitamin D is reported in ng/mL or nmol/L, 2.5x apart, and the 50-80 'optimal' band is a convention the Endocrine Society itself stopped endorsing in 2024.
Thyroid panel
How to read TSH, free T4, free T3, reverse T3 and thyroid antibodies — including why testosterone lowers total T4 with no thyroid disease at all.
DHT (dihydrotestosterone)
Dihydrotestosterone is more than a hair-loss number. What a serum DHT can and cannot tell you, why gels raise it, and what 5-ARI suppression really costs.
Where to log the results
The TherapyLog app reads a lab report against your own printed reference interval first and a generic one only when your report did not carry one, keeps the assay method with the value, and charts the trend. It runs in the browser and needs no account — open it here. The user guide covers the bloodwork tab in detail, the calculators cover the dosing arithmetic, and the compound pages cover what moves each of these markers.
Logging a marker with its unit, its printed reference interval and its assay method beside it is what makes a trend mean anything.
Log your bloodworkThis calculator does the arithmetic you typed and nothing else. It does not know what is actually in your vial, whether the label is accurate, or anything about you. Confirm the vial strength and the diluent volume on your own label before you draw, and take dosing decisions to a qualified provider.