Age-Related Changes in the Genitourinary System
As one ages, the reserve capacity of the kidney is decreased. This makes the individual more vulnerable to dysfunction if demands on the kidney increase, as in trauma or disease. The number of nephrons decreases, and the length of the tubules decreases. Reduction of blood flow also occurs. As a result, kidney function de-creases, with slower rate of filtration in the glomeruli and less production of renin, vitamin D, and erythro-poietin. Response to ADH is diminished. All of these changes result in diminished function.
The regulation of blood volume is less efficient, with the ability to concentrate and dilute the urine also diminished. Reduced vitamin D production af-fects the absorption of calcium from the intestine (both functions of the hormones). Reduced produc-tion of erythropoietin may contribute to anemia. The tubular changes result in difficulty in maintaining acid-base balance.
One important effect of changes in kidney function is the reduced capacity to excrete drugs. If care is not taken to reduce drug dosages, drugs may accumulate in the body and produce further complications of overdose. Also, when fluids are administered par-enterally or diuretics are given to elderly persons, they need to be monitored carefully because such in-terventions may severely challenge the water and solute balance of the body.
There may be reflux of urine into the ureters from the bladder as a result of improper functioning of the junction between the ureter and bladder.
Smooth muscle and elastic tissue degenerate with time, being replaced with fibrous tissue and a de-creased bladder capacity. The muscles become weaker and incomplete emptying of bladder may occur. The decrease in bladder capacity results in increased frequency of urination. In men, prostate hypertrophy is common. Because the urethra passes through the prostate, growth of the prostate may obstruct the urethra, producing difficulty in passing urine. Weakening of the pelvic muscles may result in stress incontinence (i.e., leakage of small quantities of urine when the intra-abdominal pres-sure is increased).
One common problem faced by elderly individuals is difficulty maintaining bladder control. Individuals with this problem often avoid public places or, by re-stricting their fluid intake, avoid embarrassment. It is important to put them at ease. As a result of inconti-nence, many elderly individuals may need catheteri-zation or diapers. Rashes and other skin lesions may be present in the lumbar and gluteal regions as a re-sult of irritation of the sensitive skin. Such inflamed areas should be avoided.