Yasmin Williams - HEALTH-WISE IN THE past, I have highlighted the fact that the kidneys are target organs for damage from diabetes and hypertension.
These conditions can produce gradual and silent loss of renal or kidney function, referred to as chronic renal failure. Total/nearly total loss of function is referred to as end stage renal failure. This is in contrast to acute renal/kidney failure, caused by pre-renal, renal and post-renal conditions, which results in a rapid decrease in kidney/renal function (over days or weeks) either with or without urine production.
Pre-renal causes include loss of blood and other body fluids, renal causes involve damage to the nephrons, which make up the kidney substance and post-renal causes include obstruction of ureters (tubes leading from the kidneys to the bladder) and obstruction of the bladder, which together with the kidneys and the urethra (tube which takes urine to the exterior of the body) constitute the urinary system. The urethra in the male runs along the length of the penis before it exits the body, while in the female, the shorter urethra exits the body, at the anterior aspect of the vagina. More commonly we speak about the genitourinary system.
BREAKDOWN PRODUCTS
The kidneys are responsible for removing waste products from the body, for example, urea and creatinine. The kidneys are also responsible for regulating needed electrolytes (sodium, calcium, phosphate, potassium) and water. All these activities take place in the nephron, which is the smallest functioning unit of the kidney. The breakdown products of the various activities in the body, including digestion of food eaten, are brought in the blood to the nephron where there is 'chemical exchange' resulting in waste and water moving into the ureters and bladder for excretion/elimination as urine.
Additionally, the kidneys produce erythropoietin, a substance which stimulates the bone marrow to make red cells contain haemoglobin needed to carry the life-giving oxygen to the body's cells. The kidney produces another substance called renin, which is important for regulating blood pressure and it also produces a form of vitamin D which is important for bone health and calcium regulation.
Patients with chronic renal failure may have no symptoms. In these cases renal dysfunction can only be detected by doing laboratory tests. A person with mild to moderate dysfunction may have non-specific symptoms. Nocturia or urination at nights may be a presenting symptom highlighting the loss of the kidney's ability to concentrate urine during the night. Fatigue and decreased mental alertness may be two other presenting symptoms indicating that blood levels of urea are increasing.
BE ALERT
Patients with chronic renal failure should be alert to factors producing or aggravating that condition. For example, kidney- damaging substances (nephrotoxins for example, certain medication), infection, high blood calcium, obstruction to urinary system, heart failure and conditions causing depletion of sodium (salt) and water.
Dialysis and kidney transplant are required with progressive disease and toxic levels of the waste product urea. There are many causes of chronic renal failure. However, it is important for me to stress that the most common cause of end-stage renal disease has been reported as due to diabetes followed by damage cause by hypertension (nephroangiosclerosis). It is, therefore, important that diabetic and hypertensive patients understand the 'natural history' of the conditions and take on the challenge of appropriate management.
Controlling high blood sugar levels in diabetic kidney disease (diabetic nephropathy) and controlling hypertension substantially reduce deterioration of kidney function. It is thought that drugs called 'ace inhibitors' (used to control hypertension) and ossibly 'angiotensin receptor blockers', are important in preventing decline in kidney function. Each diabetic, even those not hypertensive, should ask about being placed on a small dose of an ace inhibitor for its 'kidney-sparing effect'.
Dr. Yasmin Williams is a family doctor and public health specialist; email: yourhealth@gleanerjm.com.
