Hot flashes

A hot flash is an abrupt episode of intense warmth — usually face, neck and chest — typically lasting 1–5 minutes, often followed by sweating and then chilling. The underlying mechanism is a brief dysregulation of the hypothalamic thermoregulatory set point, causing inappropriate vasodilation and sweating to dump heat that wasn't actually excessive. By far the commonest cause is the perimenopausal oestrogen decline in women aged 45–55, where 75–80% experience symptoms over an average of 4–7 years. But hot flashes can mimic that pattern in: hyperthyroidism (paired with weight loss, palpitations, tremor); diabetes (especially nocturnal hypoglycaemia); carcinoid syndrome (flushing + diarrhoea + wheezing); mast-cell activation syndrome (flushing + itch + GI symptoms); pheochromocytoma; some medications (SSRIs, opioids, tamoxifen, GnRH analogues, vasodilators).

• Perimenopause / menopause — overwhelmingly the commonest in women >40; oestrogen withdrawal.
• Andropause / testosterone deficiency — analogous in men with low T or post-androgen-deprivation therapy.
• Hyperthyroidism — weight loss, palpitations, heat intolerance, tremor.
• Hypoglycaemia — diabetics on insulin/sulfonylureas; sweating with shakiness, often pre-meal.
• Carcinoid syndrome — flushing + diarrhoea + occasional wheezing.
• Mast-cell activation — flushing + itch + GI symptoms.
• Pheochromocytoma — paroxysmal flushing + sweats + hypertension + headache.
• Medications — tamoxifen, GnRH analogues, SSRIs, opioids, calcium-channel blockers.
• Alcohol, spicy food, anxiety — benign triggers.

First-line panel by clinical picture: TSH and free T4 (always); fasting glucose + HbA1c if diabetic risk; if classic perimenopause picture lab work is rarely needed (clinical diagnosis). Suspicion of carcinoid: 24-hour urine 5-HIAA + serum chromogranin A; pheochromocytoma: plasma or 24-hour urine metanephrines. Mediora.AI interprets the panel — high TSH plus borderline glucose is a different story from isolated perimenopausal pattern.