MODULE SUPPLEMENT: RENAL SYSTEM
Changes in Renal Homeostatic Controls

Renal function is influenced by numerous locally produced and systemic neuro-hormones including antidiuretic hormone (vasopressin), aldosterone, and atrial natriuretic peptide.

Antidiuretic Homone (ADH)

Levels of ADH do not appear to decrease with age. However, its release may become more sensitive to changes in osmolality, but less sensitive to baroreceptor stimulation. In addition, the renal tubules appear to become increasingly resistant to its effects (McKenna & Thompson, 1998).

Renin-Angiotensin-Aldosterone System

Renin, produced by the juxtaglomerular cells, decreases with age.

Mrs. Jones, an 85 year old woman, comes to clinic for a check of her blood pressure. She had been told to follow a low sodium diet which she follows religiously. She now complains of increased weakness.

Atrial Natriuretic Peptid (ANP)

Until recently, ANP has not been the focus of much attention. Produced in the atria, ANP facilitates sodium excretion and can help counteract vasoconstrictive forces in the kidney. ANP levels increase with age, although exactly why is not clear. Changes in atrial pressure may be a factor. Increased levels of ANP contribute to the propensity of older adults to 'waste sodium.'