Endocrine Abstracts

Introduction: Hypertension is often associated with autosomal dominant polycystic kidney disease (ADPKD). The pathogenesis of hypertension is complex, including intrarenal activation of the renin-angiotensin-aldosterone system (RAAS), arterial stiffness endothelial dysfunction, increased sympathetic nervous system activity and endothelin-1 secretion. However a secondary cause of hypertension should be suspected in presence of hypokaliemia and resistant hypertension.

Case report: A 51-year-old woman with a 30-year history of ADPKD was admitted to our hospital because of inadequate control of blood pressure. She had a family history of polycystic kidney disease, with an affected father and brother. The patient was diagnosed with hypertension secondary to ADPKD at the age of 35, she received treatment with betablockers, calcium blockers and angiotensin converting enzyme inhibitor. At physical examination the blood pressure was 160/100 mm Hg (no difference between arms); heart rate was 70 beats/min and body mass index was 28.48 kg/m². Laboratory findings revealed mild hypokalemia 3.4 mmol/l with inappropriate kaliuresis 53, mmol/24H, increased serum creatinine at 110 umol/l with an estimated glomerular filtration rate (GFr) : 50 ml/min. After therapeutic adjustement, management of hypokalemia and normal salt diet, endocrine evaluation revealed high plasma aldosterone concentration at 583 pg/ml >200 pg/ml, suppressed plasma renin activity, aldosterone/renin ratio of 74, 36 >23 confirmed the diagnosis of primary aldosteronism (PA). Abdominal computer tomography (CT) without contrast revealed an adenoma in the left adrenal gland of 13 mm. The surgical excision of the adenoma was considered but it was excluded due to the difficult surgical approach, and therefore the patient started spironolactone (a mineralocorticoid-receptor blocker) at 50 mg once daily. After medical treatement, the patient’s blood pressure normalized (120/80 mmHg) as did her serum potassium level (4.0 mmol/l) without impairment of kidney function.

Discussion: The diagnosis of primary aldosteronism in a patient with polycystic kidney disease is challenging because: the renal cysts may obscure an adrenal adenoma; polycystic kidney disease itself is often complicated by hypertension and hypokalemia can be obscured by renal insufficiency. The association of ADPKD and PA is rare but once the coexistence of hypokalemia and resistant hypertension is identified in ADPKD patients, a secondary cause of hypertension should be considered, like PA.