Isolated hypoaldosteronism is a rare condition. It can present with postural hypotension with or without significant hyponatraemia, hyperkalemia or heart block. For patients with Hypoaldosteronism, pregnancy raises issues regarding management of hyperkalemia and adequate blood pressure maintenance. A 17 yr girl presented with symptoms of tiredness, dizziness and routine blood test revealed marked isolated hyperkalemia (Serum potassium 7.1 mmol/L) with normal renal function. She had several investigations including 24 hour urine potassium, urinary catecholamines, Serum aldosterone & renin measurements, fasting blood glucose, short synacthen test and autoimmune profile, all of which were normal. She refused genetic testing and was diagnosed with isolated hyperaldosteronism based on laboratory findings and started on Fludrocortisone 100 mcg OD. At age 25 yr, she was seen in joint antenatal-endocrine clinic. She was G5P2 (previous 2 premature live births, 1 still birth at 25 weeks gestation and 1 miscarriage). She was asymptomatic, BP 120/80, no signs of cortisol or androgen excess. She was taking Fludrocortisone 100 mcg OD. At booking, hyperkalemia (K - 6.5 mmol/L) with normal kidney function test and venous bicarbonate was noted. Throughout her pregnancy, she was closely monitored with fortnightly blood pressure, urea & electrolytes measurements, and taking into account normal physiological changes in serum aldosterone levels during pregnancy, her Fludrocortisone dose was adjusted. During third trimester, Fludrocortisone requirement increased to 300 mcg OD and at 37 weeks gestation, healthy baby girl was delivered. During postpartum, her Fludrocortisone requirements have reduced to 100 mcg OD (pre-pregnancy levels). The effects on potassium homeostasis during pregnancy in isolated Hypoaldosteronism are less clear, mainly due to its rarity. This case highlights importance of carefully adjusting dose of Fludrocortisone to correct hyperkalemia and avoiding high blood pressure which in itself has negative impact on pregnancy outcome and the need to closely monitor such patients in specialist clinic.
Declaration of interest: There is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported.
Funding: No specific grant from any funding agency in the public, commercial or not-for-profit sector.