How to Read Your Blood Work Results Like a Pro

Why "Normal" Does Not Mean Optimal

The reference range printed next to every value on your lab report is a statistical construct. It represents the central 95th percentile of results from the lab's tested population 1. That population includes people with undiagnosed conditions, sedentary lifestyles, and subclinical deficiencies. A value landing inside the range does not guarantee health. It means you are not a statistical outlier.

The American Association of Clinical Endocrinologists (AACE) has noted that population-based reference intervals "may not reflect evidence-based decision limits for disease risk" 2. A fasting glucose of 99 mg/dL sits inside most labs' reference range but already meets ADA criteria for impaired fasting glucose. A total testosterone of 280 ng/dL may pass the lower reference cutoff at some laboratories, yet the Endocrine Society's 2018 guideline identifies values below 300 ng/dL (confirmed on two separate morning draws) as the diagnostic threshold for male hypogonadism [3].

The practical takeaway: treat reference ranges as guardrails, not goals. Every section below identifies both the standard range and the clinical decision points that actually drive treatment.

The Complete Blood Count (CBC)

The CBC is usually the first panel on your report. It quantifies red cells, white cells, and platelets. For men, and especially men on TRT, three lines deserve close attention: hemoglobin, hematocrit, and red blood cell count.

Hemoglobin carries oxygen. The typical male reference range runs 13.5 to 17.5 g/dL 4. Hematocrit measures the percentage of blood volume occupied by red cells. Testosterone stimulates erythropoiesis through EPO upregulation, so TRT predictably raises both values. The Endocrine Society's 2018 clinical practice guideline recommends checking hematocrit at baseline, at 3 to 6 months after starting TRT, and then annually, with a dose reduction or temporary hold if hematocrit exceeds 54% 3.

White blood cell (WBC) counts between 4,000 and 11,000 cells/µL are standard. A count above 11,000 usually signals infection or inflammation. Platelet counts between 150,000 and 400,000/µL support normal clotting. Persistent values outside those windows warrant follow-up regardless of symptoms.

The Comprehensive Metabolic Panel (CMP)

This 14-test panel covers electrolytes, glucose, kidney markers, and liver enzymes. Think of it as a system-status dashboard.

Glucose and HbA1c. Fasting glucose between 70 and 99 mg/dL is considered normal by the American Diabetes Association. Values of 100 to 125 mg/dL indicate prediabetes. HbA1c, which reflects average blood sugar over roughly 90 days, classifies prediabetes at 5.7% to 6.4% and diabetes at 6.5% or above 5. In the Diabetes Prevention Program trial (N=3,234), lifestyle intervention reduced progression from prediabetes to type 2 diabetes by 58% over 2.8 years 6.

Kidney function. Creatinine and blood urea nitrogen (BUN) feed into the estimated glomerular filtration rate (eGFR). An eGFR persistently below 60 mL/min/1.73 m² for three or more months meets the KDIGO definition of chronic kidney disease stage 3 7. Mild creatinine elevations can also reflect high muscle mass, so context matters.

Liver enzymes. AST (aspartate aminotransferase) and ALT (alanine aminotransferase) reference ranges typically cap at 40 U/L. ALT is more liver-specific. AST rises after heavy resistance training, sometimes doubling within 24 hours of a hard session 8. If your draw follows a workout, tell your clinician. The American College of Gastroenterology recommends using sex-specific upper limits of normal: 33 U/L for men and 25 U/L for women for ALT 9.

The Lipid Panel

Four numbers. Each one tells a different part of the cardiovascular story.

Total cholesterol is the sum of LDL-C, HDL-C, and VLDL-C. By itself, it is the least informative value on the panel. LDL-C (low-density lipoprotein cholesterol) drives atherosclerosis. The 2018 AHA/ACC cholesterol guideline ties LDL-C targets to 10-year ASCVD risk rather than a single universal cutoff 10. For patients with clinical ASCVD, an LDL-C goal below 70 mg/dL (and sometimes below 55 mg/dL with very high risk) is standard. For primary prevention in lower-risk adults, keeping LDL-C below 100 mg/dL is a common target.

HDL-C above 40 mg/dL in men is the conventional minimum. Triglycerides below 150 mg/dL are considered normal, though values above 500 mg/dL create acute pancreatitis risk and require urgent management 10.

Testosterone therapy's effect on lipids varies by formulation. A meta-analysis of 30 RCTs found that injectable testosterone modestly reduced HDL-C (weighted mean difference of approximately -2.4 mg/dL) without consistent changes in LDL-C 11. Monitoring lipids at least annually on TRT is appropriate.

The Hormone Panel: Testosterone, Estradiol, and Beyond

Reading a hormone panel requires understanding four interconnected values.

Total testosterone. Most labs list a reference range of roughly 264 to 916 ng/dL based on the Harmonized Reference Ranges study 12. Morning draws (before 10 AM) are essential because testosterone follows a circadian pattern, peaking in early morning and dropping 20% to 25% by late afternoon. A single low value is not diagnostic. The Endocrine Society requires confirmation on a second morning sample 3.

Free testosterone. Only 1% to 3% of circulating testosterone is unbound. Calculated free testosterone (using the Vermeulen equation) is preferred over direct analog immunoassay, which underestimates true free T 13.

SHBG (sex hormone-binding globulin). This carrier protein binds testosterone tightly. High SHBG (common with aging, hyperthyroidism, and liver disease) can produce a "normal" total T with low free T. Low SHBG (associated with obesity, insulin resistance, and type 2 diabetes) inflates free T relative to total T. You cannot interpret total testosterone without knowing SHBG.

Estradiol (E2). Testosterone aromatizes to estradiol. On TRT, E2 can rise enough to cause gynecomastia or fluid retention. The Endocrine Society does not endorse routine estradiol targets but recommends checking E2 when symptoms suggest excess 3.

LH and FSH. These pituitary hormones distinguish primary hypogonadism (high LH/FSH, low T) from secondary hypogonadism (low or inappropriately normal LH/FSH, low T). On exogenous TRT, both will be suppressed to near zero. That is expected. If you are not yet on TRT, LH and FSH help identify the cause.

Thyroid Markers: The Fatigue Overlap

Many men pursue testosterone testing for fatigue, brain fog, or weight gain. Hypothyroidism produces the same symptoms. A standard thyroid screen includes TSH and free T4.

TSH between 0.4 and 4.0 mIU/L is the conventional reference interval. The American Thyroid Association's 2014 guideline notes that TSH alone is sufficient for initial screening in most patients 14. Free T4 confirms the diagnosis when TSH is abnormal. Subclinical hypothyroidism (TSH between 4.5 and 10 mIU/L with normal free T4) affects approximately 4% to 8.5% of the U.S. adult population per NHANES data 15. Symptoms may or may not be present, but the finding is worth tracking over time.

Dr. Shalender Bhasin, Professor of Medicine at Harvard Medical School and lead author of the Testosterone Trials, has stated: "Clinicians should exclude thyroid dysfunction, depression, and sleep apnea before attributing symptoms solely to androgen deficiency" 3. Ordering a thyroid panel alongside testosterone is good practice for any initial workup.

Inflammatory and Metabolic Markers Worth Adding

Standard panels do not always include the tests with the highest predictive value. Two additions are worth requesting.

High-sensitivity C-reactive protein (hs-CRP). This marker of systemic inflammation independently predicts cardiovascular events. In the JUPITER trial (N=17,802), rosuvastatin reduced major cardiovascular events by 44% in patients with LDL-C <130 mg/dL but hs-CRP ≥2.0 mg/L 16. The AHA/CDC classifies hs-CRP below 1.0 mg/L as low risk, 1.0 to 3.0 mg/L as moderate risk, and above 3.0 mg/L as high risk 17. A single elevated reading should be repeated after two weeks to rule out acute infection.

Fasting insulin. Not part of a standard CMP or lipid panel, fasting insulin can detect insulin resistance years before glucose or HbA1c become abnormal. Values above 10 to 15 µU/mL (lab-dependent) may indicate early metabolic dysfunction. As endocrinologist Dr. Robert Lustig of UCSF has noted, "By the time fasting glucose rises, you've already lost 50% of your beta-cell function" 18. Requesting fasting insulin alongside glucose provides a much earlier warning signal.

PSA and Prostate Monitoring on TRT

Prostate-specific antigen (PSA) screening has a complicated history, but its role in TRT monitoring is more straightforward. The Endocrine Society guideline recommends a baseline PSA before starting testosterone therapy and repeat testing at 3 to 6 months, then at 12 months, then annually 3.

A PSA above 4.0 ng/mL, or a rise greater than 1.4 ng/mL within any 12-month period, should prompt urological evaluation before continuing TRT. The guideline also recommends a digital rectal exam at baseline and follow-up, though some clinicians now rely on PSA kinetics and MRI. A 2016 meta-analysis of 22 RCTs found no significant increase in prostate cancer incidence with testosterone therapy compared to placebo (OR 0.87 to 95% CI 0.30 to 2.50) 19. TRT does not appear to cause prostate cancer, but it can stimulate growth of undetected existing disease. Monitoring is non-negotiable.

How to Build a Monitoring Schedule

The frequency of lab work depends on whether you are establishing a baseline, titrating a new therapy, or in stable maintenance.

Pre-TRT baseline. Total testosterone (two morning draws), free testosterone or SHBG, CBC, CMP, lipid panel, PSA, estradiol, LH, FSH, TSH, free T4, prolactin, and HbA1c. This panel costs between $200 and $500 at direct-pay labs.

First year on TRT (titration). Repeat testosterone, hematocrit, PSA, estradiol, and liver enzymes at 6 weeks, 3 months, 6 months, and 12 months. Adjust dose based on trough testosterone (drawn at the nadir before next injection for injectable formulations) 3.

Annual maintenance. Full panel once yearly if stable. Add lipids and HbA1c. Continue hematocrit and PSA monitoring indefinitely.

Document every result. A single snapshot is far less useful than a trend line over 6, 12, or 24 months. Most patient portals allow CSV export. A simple spreadsheet with date, marker, and value columns turns isolated numbers into patterns that you and your clinician can act on.

The minimum clinically meaningful shift for total testosterone between draws is roughly 15% to 20%, accounting for biological and analytical variability 12. Smaller fluctuations between two draws are expected and usually do not require dose changes.