Serum aldosterone changes during hyperinsulinemia are correlated to body mass index and insulin sensitivity in patients with essential hypertension.
OBJECTIVE
To measure the effects of hyperinsulinemia on serum electrolyte status and associated hormones, and on serum free fatty acid (FFA) concentrations, in patients with essential hypertension.


METHODS
The serum electrolyte status (Na, K, Ca, ionized Ca, Mg, P, pH) and associated hormones [plasma renin activity (PRA), serum parathyroid hormone (PTH) and aldosterone concentrations], and FFA were measured during an euglycemic hyperinsulinemic clamp test in 49 patients with untreated essential hypertension.


RESULTS
Serum potassium, phosphate, PTH, and FFA concentrations decreased during hyperinsulinemia, while serum ionized calcium concentration, pH, and PRA increased significantly (P < 0.05). The changes in serum potassium and magnesium were both inversely related to the insulin-mediated glucose uptake (r= -0.62, P< 0.0001; r= -0.31, P< 0.05, respectively). Both body mass index (BMI) and insulin-mediated glucose disposal were significantly correlated to the changes in serum aldosterone concentration during hyperinsulinemia (r = 0.41, P < 0.01; r = -0.40, P < 0.01, respectively). The change in serum aldosterone during the clamp test was not significantly related to the change in PRA, but tended to correlate to the change in potassium concentration (r= 0.25, P= 0.10). A less pronounced reduction in FFA during induced hyperinsulinemia was associated with low insulin sensitivity (r= -0.35, P< 0.05).


CONCLUSIONS
Hypertensive patients with normal BMI and a more pronounced glucose uptake showed a larger serum potassium decline and lowered aldosterone concentrations during induced euglycemic hyperinsulinemia. Insulin-resistant patients showed a less pronounced reduction in FFA during hyperinsulinemia. The observations in the present study may indicate that alterations in aldosterone and FFA metabolism might be linked to the insulin resistance metabolic syndrome.
Haenni
A
A
Department of Public Health and Caring Sciences/Geriatrics, Uppsala University, Sweden. arvo.hanni@geriatrik.uu.se
Reneland
R
R
Lind
L
L
Lithell
H
H
D000450:Aldosterone / Q000097:blood*; D015415:Biomarkers / Q000097:blood; D001786:Blood Glucose / Q000378:metabolism*; D001794:Blood Pressure; D015992:Body Mass Index; D002118:Calcium / Q000097:blood; D018450:Disease Progression; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005260:Female; D005951:Glucose Tolerance Test; D006801:Humans; D006946:Hyperinsulinism / Q000097:blood* / Q000150:complications; D006973:Hypertension / Q000097:blood / Q000150:complications*; D007328:Insulin / Q000097:blood*; D007333:Insulin Resistance; D008297:Male; D008875:Middle Aged; D010281:Parathyroid Hormone / Q000097:blood; D010710:Phosphates / Q000097:blood; D011188:Potassium / Q000097:blood; D012083:Renin / Q000097:blood
D015415:Biomarkers; D001786:Blood Glucose; D005230:Fatty Acids, Nonesterified; D007328:Insulin; D010281:Parathyroid Hormone; D010710:Phosphates; D000450:Aldosterone; D012083:Renin; D011188:Potassium; D002118:Calcium