The Renin-Angiotensin-Aldosterone System in Patients with Cystic Fibrosis of the Pancreas

Abstract

ExtractPatients with cystic fibrosis of the pancreas (CFP) have elevated plasma renin activity, supine renin 497-595 compared with a normal value of 228 ± 133 ng/100 ml plasma on 109 mEq sodium intake/24 hr, but have normal renin release mechanisms as far as postural changes are concerned, since the renin activity increases normally with the upright posture; upright renin, 594-875 compared with a normal value of 359 ± 210 ng/100 ml plasma on the same sodium intake. The high aldosterone secretion rates (ASR), 161 -4-45 compared with a normal value of 90 ± 31 /jg/24 hr, seen on 109 mEq sodium intake were probably secondary to the abnormally high renin release. The same can be said for the lack of adequate suppression to normal of both renin and ASR on 249 mEq sodium intake/24 hr, supine renin 205-544 compared with a normal value of 97 ± 71 ng/100 ml plasma; upright renin 845-893 compared with a normal value of 212 ±61 ng/100 ml plasma; ASR on the same intake, 93-333 compared with a normal value of 62.15 ± 27.8 /ug/24 hr. The low metabolic clearance rates and the high calculated plasma aldosterone concentrations on the 109 mEq sodium intake indicate that a state of secondary hypcraldosteronism exists in patients with CFP, probably as an adaptation to frequent, excessive sodium losses via the sweat and consequent contraction of intravascular volume. SpeculationIn all the patients that we studied with cystic fibrosis of the pancreas a state of secondary hyperaldosteronism appears to exist. This state of hyperaldosteronism, secondary to increased renin release, probably results from adaptation to frequent, excessive sodium losses via the sweat, leading to depletion of extracellular fluid volume.

Exercise and Heat Stress in Cystic Fibrosis Patients

“…~urthermore, CF patients may have decreased serum electrolvte concentrations as the first recognizable manifestation of theirhisease (2, 11). Several investigat&s have discussed possible sequences of events which occur with salt depletion in CF (6,12). But experimental documentation that CF patients actually lose large amounts of salt in their sweat and are thus really at risk for developing heat illness has not been published.…”

En syv måneder gammel jente med svette føtter

“…Det økte aldosteronnivået vil føre til økt kaliumtap både i svetten og i urinen og derigjennom hypokalemi (5). Pasientens høye reninaktivitet og normale aldosteronnivå kan kanskje forklares av at lavt serum-kalium kan nedregulere aldosteronfrigjøringen (6).…”

Hypomagnesaemia in cystic fibrosis patients referred for lung transplant assessment

“…There are several other reasons why CF patients may be prone to hypomagnesaemia including CF related diabetes mellitus, secondary hyperaldosteronism [11] and malabsorption. In patients with diabetes mellitus, the diuresis induced by glycosuria results in increased urinary sodium and magnesium losses [10].…”