Endocrine Abstracts

Adrenocortical insufficiency is a life-threatening hormonal deficiency which is readily treatable, but which commonly presents with longstanding, vague symptomatology. ACTH deficiency (the most common cause) requires only glucocorticoid replacement while patients with Addison's disease are also deficient in aldosterone and require fludrocortisone replacement.

Hydrocortisone is the standard form of glucocorticoid replacement, and directly replaces the missing active hormone - cortisol. However, the normal pattern of diurnal cortisol secretion is difficult to mimic precisely with oral therapy. We recommend thrice daily hydrocortisone, with a usual starting dose of 10mg on rising, 5mg at lunchtime and 5mg evening, since traditional twice-daily regimes more frequently result in elevated morning plasma cortisol and 24h urine free cortisol despite persistently low plasma cortisol prior to the evening dose which may be associated with non-specific symptoms at this time. Replacement levels can be easily monitored with a hydrocortisone day curve: we measure plasma cortisol at 09:00 (after taking the morning dose on rising), 12:30 and 17:00 (before lunchtime and evening doses) and collect 24h urine free cortisol (UFC). We look for 09:00 cortisol and UFC to be in the normal range (to avoid over-replacement) and 12:30 and 17:00 cortisol to be >50nmol/L (and ideally >100nmol/L) to avoid symptoms of under-replacement.

Patients require appropriate education to adjust their hydrocortisone doses during intercurrent illness. They should also have a steroid card and/or alert bracelet - and we have recently developed a personalised blue 'Steroid Replacement Card' - incorporating patient clinical details printed from our patient information system. Patients should have an ampoule of hydrocortisone for emergency use - and those who are prepared to do so should learn to inject it themselves.

Particular issues to be discussed include appropriate assessment and treatment for patients with borderline results to dynamic tests, CAH and those receiving high dose steroids for other medical conditions.