Bloodwork Basics
How to Choose Which Blood Tests to Order: A Guide to Building Your Own Panel
A category-by-category tour of the individual lab tests athletes order most—what each one measures, what it can and cannot show, and when a full panel is the better choice.
Ordering bloodwork one test at a time sounds simple until you see the list. Two testosterone assays. Four thyroid markers. A metabolic panel that already includes several things you were about to add separately. The question is not “which tests are good” — most of them are useful in the right context. The question is which ones answer the question you actually have.
This guide walks through the main categories of individual lab tests, what each one measures, and where the common overlaps sit. It is educational context, not a recommendation of what to order. What belongs on a requisition depends on your history, symptoms, medications, and what a healthcare professional thinks is worth measuring.
Start with the question, not the test list
Before picking anything, it helps to name what you are trying to learn. A few common starting points:
- A baseline. You have never had bloodwork and want a reference point to compare future results against.
- A specific symptom or concern. Fatigue, low libido, unexplained weight change, or a family history you want to take seriously.
- A follow-up. A previous result was borderline or unexpected and someone suggested rechecking it.
- Monitoring. You are tracking something over time under professional guidance.
These lead to very different requisitions. A single follow-up marker is a reasonable à-la-carte order. A first-ever baseline usually is not — that is the case where a panel covers more ground for less money, which we come back to at the end.
Hormone markers
Testosterone is the most commonly requested single test, and it comes in more than one form. A total testosterone value describes the whole circulating amount; a free value estimates the fraction not bound to carrier proteins. Assay method also matters — the sensitive LC/MS variant resolves the low end more precisely than a standard immunoassay, which is why it is the one used in the men’s panels. We cover the distinction in detail in Total vs. Free Testosterone.
SHBG (sex hormone binding globulin) is the protein that binds most circulating testosterone. It provides context for why a free value might look different from what the total suggests, and it can shift with thyroid status, liver health, insulin, age, and medications.
Estradiol is often ordered alongside testosterone. As with testosterone, there is a standard assay and a sensitive one; the sensitive method gives better resolution at the low concentrations typical in men, while the standard assay is generally adequate across the female range.
LH and FSH are pituitary signals. Their main interpretive value is directional: they can help a clinician distinguish a problem originating in the gonads from one originating in the signalling above them. On their own, without the downstream hormone, they answer very little.
Prolactin, DHEA-sulfate, cortisol, and IGF-1 each add a specific slice of context — pituitary and adrenal output, and growth-hormone-related activity. Cortisol in particular is time-sensitive: it follows a daily rhythm, so a value drawn in the afternoon is not comparable to a morning one, and most reference ranges assume a morning draw.
PSA is a prostate screening marker rather than a performance one. It commonly appears beside testosterone because monitoring recommendations exist for some men. Screening decisions are individual, so it belongs in a conversation with a clinician rather than on a checklist.
Thyroid markers
Thyroid testing has a natural order of operations. TSH with Free T4 is the standard starting pair, and for most people it is where the question is answered. Free T3 and Reverse T3 are downstream markers that add nuance in specific situations — notably during a prolonged calorie deficit, when T3 commonly falls without indicating thyroid disease.
Ordering the downstream markers first, without TSH and Free T4, is one of the more common à-la-carte mistakes: it produces numbers that are hard to interpret in isolation. Our thyroid panel guide explains what each marker represents and why sequence matters.
Metabolic markers
The comprehensive metabolic panel (CMP) is the broadest single order on most lists. It bundles fourteen measurements — kidney markers including creatinine and eGFR, liver enzymes AST and ALT, electrolytes, protein, and glucose. Because it is inexpensive relative to its coverage, adding separate tests that duplicate it is usually wasted money.
Things that genuinely add to it:
- Hemoglobin A1c reflects roughly three months of average blood sugar and is not captured by a single fasting glucose.
- Fasting insulin pairs with A1c to describe insulin sensitivity, which glucose alone does not show.
- GGT is a liver marker that adds specificity to the CMP’s AST and ALT — useful because AST and ALT can also rise from muscle, especially after hard training. See Can Hard Training Raise AST and ALT? for why that matters to athletes.
- Cystatin C estimates kidney filtration without depending on muscle mass, which is the specific limitation of creatinine in very muscular people.
Cardiovascular markers
A lipid panel covers total cholesterol, LDL, HDL, triglycerides, and the cholesterol-to-HDL ratio. It is the standard starting point and the measurement most guidelines are built around.
ApoB approximates the number of atherogenic particles rather than the cholesterol they carry, which is a different measurement from LDL-C and can add information in some situations — particularly when triglycerides or metabolic conditions complicate the lipid picture. Our ApoB guide covers where it fits and where it does not.
High-sensitivity CRP measures systemic inflammation. It is easily disturbed by recent illness, injury, or hard training, so the timing of the draw affects how much a single value means.
Blood, iron, and vitamins
A CBC with differential covers red cells, white cells, platelets, hemoglobin, and hematocrit. Like the CMP, it is broad and inexpensive, which makes it a common foundation rather than an add-on.
Ferritin reflects iron storage and is usually the first iron marker to move in a developing deficiency. Iron and TIBC add transport-side detail. Ferritin is also an acute-phase reactant, meaning inflammation can raise it independently of iron status — one of several reasons the number needs interpretation rather than a straight comparison to a range. We go deeper in Ferritin and Iron for Athletes.
Vitamin D (25-hydroxy) and Vitamin B12 round out the common nutrient markers, relevant to bone health, immune function, energy metabolism, and nerve health.
Where à-la-carte stops making sense
Individual tests are the efficient choice when you have a narrow question: one follow-up marker, one thing a clinician asked you to recheck, one addition to recent bloodwork you already have.
They stop being efficient once the basket grows. Every order carries the same fixed overhead — the requisition, the provider’s order and review — whether it contains one test or ten. Past a certain number of selections, a pre-built panel includes more markers for less total cost. Our build-your-own page shows a running total as you select and flags the point where a panel becomes better value, because selling someone the worse deal is not a good outcome for either side.
For a broader map of what a full workup typically covers, see What Bloodwork Should Bodybuilders Get?.
Reading results afterward
Whatever you order, a result is a data point rather than a verdict. Reference ranges describe a population, not the right value for one person. Collection conditions — fasting status, hydration, recent training, time of day, illness, supplements, and medications — can all move numbers without anything being wrong.
Keep a record of those conditions alongside your results, repeat under similar conditions when you can, and take anything unexpected or persistently out of range to a qualified healthcare professional.