Endocrine Abstracts

Introduction: Acromegaly is characterized by chronic growth hormone (GH) excess and leads to numerous changes in bodily functions and comorbidity. We compared potassium homeostasis in patients with acromegaly to hypertensive controls.

Methods: We prospectively assessed serum potassium, urinary potassium excretion, aldosterone and renin, acid-base balance as well as glomerular filtration rate according to the CKD-EPI formula in 71 patients with acromegaly (37 male, 34 female; age 59±14 years) and 70 hypertensive age and gender matched patients (HP) in whom secondary hypertension was ruled out (37m, 33f; 59±14 year). Of the acromegaly patients, 23 had active disease (AD) and 48 were biochemically controlled (BC).

Results: Serum potassium levels were more elevated in patients with acromegaly (4.2 vs 4.0 mmol/l, P=0.008). Urinary excretion of potassium was also elevated in patients with acromegaly as compared to hypertensive controls (53.3 vs 35.3 mmol/l, P<0.001; 69.3 vs 52.9 mmol/g Creatinine, P=0.004). Analysis of variance in potassium excretion showed highly significant differences between AD, BC and HP (P<0.001). Post-hoc comparison revealed higher excretion in AD (66.3 mmol/l) as compared to BC (47.1 mmol/l, P=0.003) and HP (35.3 mmol/l, P<0.001; BC vs HP P=0.012). Mean arterial pressure was higher in hypertensive patients (110 vs 104 mmHg, P=0.009). There were no statistically significant differences in GFR (P=0.618), BMI (P=0.549), sodium levels (P=0.589), antihypertensive medications used (9 groups of antihypertensive drug classes; 0.117<P<1.0), aldosterone (P=0.41) and renin (P=0.161).

Discussion: We observe higher serum potassium levels in patients with acromegaly compared to patients with hypertension. Still, urinary excretion of potassium is also significantly higher despite comparable characteristics of both patient groups. Higher intramuscular potassium levels have previously been shown in acromegaly. Further research is warranted to elucidate potassium homeostasis in acromegaly.