Differentials
Addison's disease
SIGNS / SYMPTOMS
Hyperpigmentation due to high levels of adrenocorticotrophic hormone (ACTH) that stimulate melanocyte production of melanin.
Postural hypotension as the zona glomerulosa is destroyed; in contrast, the zona glomerulosa is preserved in secondary adrenal insufficiency as it is still maintained under the regulation of the renin-angiotensin-aldosterone system.
INVESTIGATIONS
ACTH level is markedly elevated.
Electrolyte abnormalities (hyponatraemia and hypokalaemia) are more common.
Primary hypothyroidism
SIGNS / SYMPTOMS
There are no classic symptom differences between patients with primary or secondary hypothyroidism. On physical examination, patients with primary hypothyroidism are more likely to have a goitre.
INVESTIGATIONS
Elevated thyroid-stimulating hormone.
Shock (cardiogenic or septic)
SIGNS / SYMPTOMS
Patients with cardiogenic shock may relate a history of prior cardiac problems.
Patients with septic shock will be febrile with an elevated white cell count.
INVESTIGATIONS
Cardiogenic shock is responsive to fluid resuscitation and septic shock is responsive to fluid resuscitation and antibiotics; in contrast, patients with hypopituitarism are unresponsive to fluid resuscitation and the haemodynamic status only improves after corticosteroids are initiated.
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