WHAT LABS SHOULD YOU ACTUALLY BE TESTING?

If You Are Experiencing Fatigue

Fatigue is one of the most common complaints and one of the least specific. Dozens of causes look identical from the outside. The right labs narrow the list fast.

Priority tests:

• • Full thyroid panel (TSH, Free T3, Free T4, TPO antibodies) — subclinical hypothyroidism is a leading cause of fatigue and is missed when only TSH is tested
• • Testosterone (total, free, bioavailable) — low testosterone causes fatigue, brain fog, and low motivation in both men and women
• • Fasting insulin and HbA1c — insulin resistance causes energy crashes even when glucose looks normal
• • Vitamin D and B12 — deficiencies in either cause fatigue and are common in the general population
• • CBC with iron studies — anemia is one of the most straightforward causes of fatigue

A comprehensive panel covers all of these. If your standard panel came back “normal” and you are still exhausted, the problem is likely in the markers that were not tested.

If You Are on TRT or Considering It

Testosterone replacement therapy requires specific monitoring before, during, and after treatment. The Endocrine Society recommends confirming low testosterone with at least two morning draws before starting therapy.

Priority tests:

• • Full hormone panel: Total Testosterone, Free Testosterone, Bioavailable Testosterone, SHBG, Estradiol, LH, FSH, DHEA-S, PSA
• • CBC — testosterone increases red blood cell production; hematocrit must be monitored to manage polycythemia risk
• • Lipid panel — testosterone therapy can shift lipid profiles
• • Liver enzymes — baseline and periodic monitoring
• • Metabolic panel — testosterone affects insulin sensitivity and metabolic markers

Once on TRT, most of these should be rechecked every 3-6 months. Hormone optimization members at Moonshot get comprehensive labs every 6 months included.

If You Are on GLP-1 Medication or Losing Weight

GLP-1 medications like semaglutide and tirzepatide cause significant metabolic changes. Rapid weight loss — whether from medication, surgery, or aggressive dieting — shifts hormones, nutrient status, and body composition in ways that need monitoring.

Priority tests:

• • Fasting insulin, fasting glucose, HbA1c — track how metabolic markers improve as weight drops; insulin sensitivity often improves before weight noticeably changes
• • Full lipid panel with ApoB and triglycerides — lipid profiles shift significantly with weight loss
• • Liver enzymes — fatty liver often improves with weight loss, and liver function should be tracked
• • Kidney function panel — rapid weight changes can affect kidney markers and electrolyte balance
• • Vitamin D, B12 — reduced food intake can accelerate nutrient depletion
• • Hormones — weight loss affects SHBG and sex hormones; testosterone often rises as body fat decreases

Retest at 3 months after starting GLP-1 medication, then every 6 months while on treatment.

If You Have Thyroid Concerns

The standard approach to thyroid screening is TSH only. That catches overt thyroid failure. It does not catch subclinical hypothyroidism, conversion problems, or autoimmune thyroid disease in its early stages.

Priority tests:

• • Full thyroid panel: TSH, Free T4, Free T3, and TPO antibodies
• • Free T3 is the active hormone — your body converts T4 into T3. If TSH and T4 look fine but T3 is low, you have a conversion problem that TSH alone will never reveal
• • TPO antibodies detect Hashimoto's thyroiditis years before TSH goes out of range — early detection changes the management approach

If you have symptoms of thyroid dysfunction (fatigue, cold intolerance, weight gain, hair thinning, constipation) and your TSH came back “normal,” the next step is a full panel — not dismissal.

If You Are Over 40

After 40, the rate of change in hormones, metabolic function, and cardiovascular risk accelerates. This is the decade when trends that started in your 30s become measurable — and when early intervention has the highest return.

The baseline panel everyone over 40 needs:

• • Full hormone panel — testosterone declines roughly 1-2% per year after 30; by 45, many men are symptomatic
• • Advanced cardiovascular markers — ApoB and Lp(a) especially; Lp(a) is genetic and only needs to be tested once, but most people have never had it checked
• • Fasting insulin, glucose, and HbA1c — insulin resistance is the precursor to most metabolic disease and often develops silently through your 40s
• • Full thyroid panel — thyroid dysfunction becomes more common with age, particularly in women
• • hs-CRP — a baseline for systemic inflammation, which correlates with cardiovascular and metabolic risk
• • Vitamin D — deficiency becomes more common as you age; affects bone health, immune function, and hormone production

Think of a comprehensive panel at 40 as establishing your reference point. You cannot track decline without a starting measurement.

Which blood panel is right for me?

It depends on your age, symptoms, and goals. Everyone over 30 benefits from a comprehensive baseline panel (60+ markers). If you are experiencing specific symptoms like fatigue, weight gain, or low energy, you may need targeted add-ons for thyroid, hormones, or metabolic health. If you are on TRT or GLP-1 medication, your provider should be monitoring specific markers every 3-6 months. A good starting point: get a comprehensive panel once, then retest based on what the results show.

Why does my doctor say my labs are “normal” when I still feel terrible?

Standard reference ranges are built from the general population — including people who are overweight, sedentary, stressed, and on medications. “Normal” means you fall within the range of average Americans, not that you are optimized. There is a significant difference between “not diagnosably sick” and “actually healthy.” A comprehensive panel with tighter optimal ranges often reveals what a standard panel misses.

How often should I get comprehensive blood work done?

Start with a comprehensive baseline. If you begin any intervention (hormone therapy, GLP-1 medication, supplementation, dietary changes), retest at 6-8 weeks. During the first year of active treatment, testing every 3-6 months helps dial in your protocol. After that, semi-annual or annual testing is sufficient for most people, unless something changes or new symptoms arise.

Do I need to fast before blood work?

Yes, for the most accurate results. Fast for 10-12 hours before your draw (water is fine and encouraged). Test in the morning, ideally between 7-10 AM, especially if hormones are being measured since testosterone and cortisol peak in the morning. Avoid intense exercise for 24-48 hours before. If you take supplements or medications, ask your provider whether to take them before or after the draw.

What is the difference between a standard blood panel and a comprehensive one?

A standard annual physical panel checks 12-15 markers and is designed to screen for disease. A comprehensive panel tests 60+ markers across 10 body systems — hormones, metabolism, cardiovascular, thyroid, liver, kidneys, blood cells, vitamins, inflammation, and cross-system patterns. The difference is asking “Am I sick?” versus “How is everything actually running?” A comprehensive panel catches problems years earlier, when you have the most options.

Which tests should I get if I am considering TRT?

Before starting testosterone therapy, you need a full hormone panel: Total Testosterone, Free Testosterone, Bioavailable Testosterone, SHBG, Estradiol, LH, FSH, DHEA-S, and PSA. You also need a CBC (to check hematocrit), a metabolic panel, and a lipid panel as baselines. Once on TRT, these markers should be monitored every 3-6 months to ensure safe and effective dosing.