Kidney disease, or Nephropathy, is the disturbance of renal function or structure, whether grossly or microscopically. Don’t bother reading the Wikipedia entry, which is highly unsatisfying to a medical professional and probably confusing and unhelpful to the non-medical person (being a Wikipedia contributor, I may need to do something about this in the future).
To understand kidney disease, we have to first touch on the physiology of the kidneys.
The human kidneys filter the blood and remove excess organic molecules (e.g. glucose) and waste products of metabolism (e.g. urea and ammonium from protein metabolism). They regulate electrolytes (salts), bodily water volume, and acid–base balance, and play an important role in blood pressure control. The kidneys also secrete hormones including calcitriol, erythropoietin, and the enzyme renin, which respectively function in calcium metabolism, red blood cell production and vascular tone.
The basic histologic unit of the kidney is the Nephron, diagrammed below:
Note that the nephron also serves to reabsorb water (via the Loop of Henle), glucose, amino acids and other substances to maintain a proper level of chemical homeostasis within the body.
There are multiple types of kidney disease, which may be categorized as acute (e.g. due to dehydration, stones, toxins or infection) or chronic. The latter may be subdivided into congenital or genetic (e.g. Polycystic kidney disease, which manifests in adulthood), obstructive (which can be caused by an enlarging prostate), intrinsic (which includes Nephrotic syndrome associated with leakage of protein and Glomerulonephritis due to auto-immune disease), or neoplastic. Chronic use of NSAIDS such as Ibuprofen can also cause nephropathy.
There are different degrees of kidney disease and symptoms will vary but may include changes in the appearance/volume of urine or frequency of micturition, hypertension and fluid retention. Kidney disease can be entirely asymptomatic in early or mild disease.
Your doctor can order screening tests which will likely include urinalysis and serum chemistry panels, an example of which is shown below.
Diabetics require yearly testing of urinary microalbumin to rule out early-stage diabetic nephropathy, the most common cause of end-stage disease requiring hemodialysis. Additional tests may include an abdominal ultrasound and 24-hour urinary collection. A CT scan is useful in evaluating for kidney stones.
