Plasma Renin Activity and Plasma Concentrations of Aldosterone, Cortisol, Adrenocorticotropic Hormone, and α-Melanocyte–Stimulating Hormone in Healthy Cats

Abstract

A pathogenetic role of the renin-angiotensin-aldosterone system has been implicated in cats in both systemic arterial hypertension and hypokalemic myopathy. Yet, measurement of plasma aldosterone concentrations (PACs) and plasma renin activity (PRA) has not unequivocally pointed to hyperaldosteronism as a cause of these conditions. To obtain appropriate reference ranges, this study included a large number (130) of healthy house cats of different breeds without a history of recent illness and plasma concentrations of urea and creatinine below the upper limit of the respective reference ranges. In addition, the pituitary-adrenocortical axis was studied by measuring plasma concentrations of adrenocorticotropic hormone (ACTH), alpha-melanocyte-stimulating hormone (alpha-MSH), and cortisol. Reference ranges for PACs (110-540 pmol/L; 40-195 pg/mL), PRA (60-630 fmol/L/s; 0.3-3 ng/mL/h), and the aldosterone to renin ratio (ARR) (0.3-3.8) were very similar to those established in the same laboratory for humans in a supine position. No breed differences were found. The ARRs in neutered cats were significantly higher than in intact cats, primarily because of low PRA in neutered cats. The ARRs of cats > or = 5 years of age were significantly higher than those of cats < 5 years of age. The plasma concentrations of ACTH, alpha-MSH, and cortisol did not correlate significantly with PAC. Thus, although blood sampling was performed in cats in nonstandardized positions and was associated with a wide variation of stress responses, the references ranges of PAC, PRA, and ARR were similar to the relatively narrow limits established for humans under standardized conditions. The effects of neutering and aging on PRA and ARR warrant further investigation.

Plasma Renin Activity and Aldosterone Concentrations in Hypertensive Cats with and without Azotemia and in Response to Treatment with Amlodipine Besylate

“…Decrease in PRA may be the result of a combination of decreased renal mass, appropriate response to increased blood pressure or could be the consequence of age. Previous studies in cats have documented that PRA decreases with age, and cats in the nonazotemic normotensive group were significantly younger than those in other groups 16. Concern is often raised regarding the diagnosis of hypertension in cats without evidence of azotemia and the potential for white‐coat hypertension.…”

Renin‐Angiotensin‐Aldosterone System Activity in Hyperthyroid Cats with and without Concurrent Hypertension

“…2,5 Although hypertension is associated with CKD in the cat, 1,3,4 the exact pathophysiologic mechanism(s) and interrelationship between the 2 conditions is still poorly understood. 6,7 Stimulation of the renin-angiotensin-aldosterone system (RAAS) occurs in human patients with CKD, [8][9][10] and this has been correlated with the severity of hypertension. 10 RAAS activation, through the effects of angiotensin-II and aldosterone, causes volume expansion, vasoconstriction, and a resultant increase in blood pressure.…”

Feline primary hyperaldosteronism: an emerging endocrine disease

“…In cats, the gold standard to differentiate the primary hyperaldosteronism from the secondary hyperaldosteronism is the aldosterone: renin ratio, being 0.3 to 3.8 the established reference value (JAVADI et al, 2004;JAVADI et al, 2005). Thus, cats with adrenocortical tumors have very high plasma aldosterone activity and, in general, completely suppressed plasma renin activity, since the secretion is independent of the stimulation of the renin-angiotensin-aldosterone system (JAVADI et al, 2005).…”

“…Moreover, few laboratories offer the plasma renin test, which often requires the clinician to use the assessment of aldosterone activity as a single test (DECLUE et al, 2005). JAVADI et al (2004) determined a reference value of 80-450pmol L -1 (28.8 to162.2pg ml -1 ) for plasma aldosterone activity from studies in healthy cats, and reported that neither stress nor body condition affected the concentrations. Nevertheless, the same authors recommend that plasma aldosterone activity should always be based on serum potassium concentrations, as hypokalemia is decisive for reduced aldosterone secretion.…”

“…Nevertheless, the same authors recommend that plasma aldosterone activity should always be based on serum potassium concentrations, as hypokalemia is decisive for reduced aldosterone secretion. Thus, an aldosterone activity at or above the laboratory reference values is inappropriate in hypertensive or hypokalemic cats (JAVADI et al, 2004;LO et al, 2014. ).…”