The kidneys are vital organs that play a crucial role in filtering waste products and excess fluids from the blood, maintaining a healthy balance of electrolytes, and producing important hormones. Therefore, the kidneys have both excretory and secretory functions.
The excretory function of the kidneys is essential for maintaining the body's homeostasis, regulating water and electrolyte balance, and acid-base balance. Additionally, metabolic waste products need to be removed from the blood. This includes a range of substances, with urea being the most significant. Urea is a nitrogen-containing compound released during protein metabolism. Another major waste product, particularly from muscle metabolism, is creatinine. Besides natural waste products, the kidneys also eliminate foreign substances such as toxins (alcohol) and medications.
The excretory product of the kidneys is urine. The composition of urine depends on the internal balance of water, electrolytes, and acids, as well as the body's metabolic status. Typically, urine is an acidic solution containing about 96% water, 2% urea, and 2% other substances, including creatinine, salts, and acids. Its yellowish color comes from the pigment of bile.
The secretory or hormonal function of the kidneys involves the secretion of three different types of hormones:
- Renin: A hormone that regulates blood pressure. It is a protein formed in the kidneys and released into the blood. Increased production, which can occur with kidney dysfunction, leads to hypertension (high blood pressure). This is managed with antihypertensive medications.
- Erythropoietin (EPO): A hormone that stimulates the bone marrow to produce red blood cells (erythrocytes). Advances in genetic engineering have allowed the production of large amounts of this hormone from cultured cells. EPO therapy has significantly improved the treatment of anemia in patients with kidney dysfunction, which affects most of these patients.
- Vitamin D: A vitamin necessary for calcium absorption from the diet. This vitamin is supplemented through diet. In the kidneys, a chemical modification process produces the active form of vitamin D. A deficiency of this vitamin leads to reduced calcium absorption, which, if prolonged, can weaken bones. For patients with kidney dysfunction, vitamin D is administered as medication.
When the kidneys fail or do not function properly, the accumulation of toxins in the body can lead to serious health complications due to reduced urine production, with water and waste products building up in the body. As kidney function deteriorates, disruptions will develop in major organ systems; this condition is called uremia. Common symptoms include fatigue, reduced appetite, nausea, and itchy skin.
Acute Kidney Failure: This can be a temporary issue, and after short-term therapy, the patient may recover. If acute kidney failure progresses to a decrease in kidney function, it is termed chronic kidney failure, which can also result from a gradual decline in kidney function over a longer period. In such cases, the kidneys are irreversibly damaged.
When kidney function drops to about 10% of its normal capacity, a special diet with reduced protein, sodium, and potassium content may be prescribed. Adhering to a strict diet can delay the need for dialysis. Other components of this conservative treatment include antihypertensive medications for blood pressure control and bicarbonate medications to correct acidosis.
When only 5% of kidney function remains, dialysis treatment is necessary, which includes hemodialysis or peritoneal dialysis, or a kidney transplant.
Dialysis involves cleaning the blood outside the body using a machine, an artificial kidney that filters waste products and excess fluids from the blood, effectively mimicking the role of healthy kidneys. Typically, hemodialysis is performed three times a week, with each treatment lasting 3-5 hours. Although dialysis can save lives, it requires commitment and regular sessions to maintain overall health and well-being.
In terms of kidney transplantation, patients face challenges such as finding a suitable kidney and the risk of rejection. After a successful kidney transplant, the patient can return to a near-normal lifestyle. The kidney can come from a living donor, preferably a close relative, or from a deceased person (cadaveric kidney). The most critical aspect is the acceptance of the donated kidney by the recipient's body. Just as with blood transfusion, the matching blood type is important, but tissue type (HLA system) should also match as closely as possible. Today, kidney transplantation is quite successful, with annual survival rates for transplanted kidneys being over 90% for kidneys from living donors and 70% for cadaveric kidneys.
Prevention is always better than treatment, and individuals can take steps to reduce the risk of kidney disease and the need for dialysis
Maintaining a healthy lifestyle, including regular exercise and a balanced diet with less salty and processed food, can help protect kidney function. Monitoring blood pressure and blood sugar levels, avoiding smoking, and limiting alcohol intake are also key preventive measures.
To preserve kidney health and reduce the risk of kidney diseases, the importance of healthy lifestyle habits and preventive check-ups cannot be overstated.
