Blood testing by symptom and condition

Start from what you have noticed rather than from a marker name. Each page sets out the symptoms people report, the markers that separate the possible causes, and the timing rules that decide whether the result means anything.

• Low testosterone: what to test before you conclude anything

  Low testosterone symptoms overlap with sleep debt, iron deficiency and thyroid problems. The markers that separate them, and how to time the draw correctly.

• Cortisol and chronic stress: what a blood test can and cannot show

  How cortisol testing works, why timing is everything, what 'adrenal fatigue' actually refers to, and which markers give the real picture.

• Thyroid testing for fatigue: why TSH alone is not enough

  TSH, free T4, free T3, reverse T3 and thyroid antibodies explained. Which markers a fatigue work-up should include and how to read them together.

• Male fertility testing: what to measure and in what order

  How male fertility testing works — semen analysis parameters, the hormone markers that explain an abnormal result, and what to do about timing.

• Iron, B12 and vitamin D: the deficiencies behind most fatigue

  Ferritin, transferrin saturation, B12, active B12, folate and vitamin D explained — which to measure, what the numbers mean, and common testing traps.

• Metabolic health testing: HbA1c, fasting insulin and what they miss

  HbA1c, fasting glucose, fasting insulin and HOMA-IR explained. Why insulin resistance appears years before glucose rises, and what to measure.

• Heart risk bloods: ApoB, Lp(a) and what a standard lipid panel misses

  Why ApoB and Lp(a) outperform LDL cholesterol alone, who should measure them, and how to read a full cardiovascular risk panel.

• Erectile difficulty: what the bloods can tell you

  Erectile difficulty is often vascular or metabolic before it is hormonal. The markers worth measuring, and why it can be an early cardiovascular signal.

• Hair loss: which blood tests are actually useful

  What blood testing can and cannot tell you about hair loss — DHT, ferritin, thyroid, vitamin D and the pattern that distinguishes shedding from genetic loss.

• Sleep, mood and hormones: the markers worth measuring

  Poor sleep drives hormonal and metabolic dysfunction in both directions. Which blood markers are worth measuring when sleep and mood are the problem.