dromlakhani Time hormonal testing for central hypogonadism in males
STEP 1 — Gather Information
Assess for acute/subacute illness, confirm overnight fast, and plan blood draw before 10 AM; order serum testosterone, FSH, LH, and prolactin.
STEP 2 — Rule In / Rule Out
Is the patient acutely or subacutely ill?
- Yes → Defer testing until illness resolves.
- No → Proceed to timing assessment.
STEP 3 — Classify or Stratify
Is the blood draw scheduled before 10 AM after an overnight fast?
- Yes → Proceed to testing.
- No → Reschedule draw to meet timing criteria.
STEP 4 — Decide
Obtain serum testosterone, FSH, LH, and prolactin; interpret low/normal testosterone with low/normal gonadotropins as central hypogonadism.
Clinical Guardrails / Mimics / Pitfalls
Do not test during acute illness, random timing, or non-fasting states; always include prolactin to rule out hyperprolactinemia; avoid relying on random cortisol or dynamic GnRH tests for this indication.
Concrete Clinical Example
A 48‑year‑old man presents with decreased libido and fatigue, no recent illness, fasting, labs drawn at 09:00 show total testosterone 220 ng/dL (low), FSH 2.1 IU/L (low‑normal), LH 3.0 IU/L (low‑normal), prolactin 12 ng/mL (normal); diagnosis of central hypogonadism is made and testosterone replacement is considered.
Source: Hormonal Replacement in Hypopituitarism in Adults: An Endocrine Society Clinical Practice Guideline, Endocrine Society, 2016, DOI:10.1210/jc.2016-2118