Hạ huyết áp (Hypotension)

Mô tả: Abnormally low blood pressure, usually less than 100 mmHg systolic.

Nguyên nhân: • Addison’s disease • Hypothyroidism

Cơ chế: Numerous causes, see Chapter 3, ‘Cardiovascular signs’. Addison’s disease Dehydration and volume loss is the primary cause of hypotension in Addison’s disease. Mineralocorticoids regulate sodium retention and potassium excretion in the urine, sweat, saliva and GI tract. A deficiency of mineralocorticoids and, to a much lesser extent, corticosteroids leads to salt wasting and failure to concentrate urine, thus producing decreased circulatory volume, dehydration and hypotension. Deficiency of glucocorticoids (adrenaline) may also lower the basal tone of the vasculature and, hence, resting systolic blood pressure.

Ý nghĩa lâm sàng: A common sign in acute primary adrenal insufficiency – up to 88% of patients exhibit hypotension.2 However, given the myriad causes of hypotension, its value as an isolated sign is limited. Conversely, the presence of hypertension is a strong negative predictor of a diagnosis of Addison’s disease.65,66