(krŏn-ĭs′ĭt-ē) The condition of being long lasting or of showing little or slow progress.
ABBR: CKD. Any illness in which kidney function remains diminished for at least 3 months without returning to normal. CKD is defined as greater than 30 mg of urinary albumin excretion per gram of urinary creatinine, or a glomerular filtration rate (GFR) of less than 60 mL/min/1.73m2 and includes both functional and structural kidney disease, abnormal urinary sediments, abnormal kidney imaging, and the presence of a kidney transplant.
INCIDENCE: CKD is present in about 14% of adult Americans. The prevalence of the disease increases with advancing age.
CAUSES: CKD is the final expression of a variety of insults to the kidney. These may include toxic exposures (such as chronic use of nonsteroidal anti-inflammatory drugs, exposure to renally toxic antibiotics, or chronic lead intoxication); chronic hypertension or diabetes mellitus; autoimmune illnesses that affect renal function (such as systemic lupus erythematosus); diseases in which proteins deposit in the urinary tubules (such as multiple myeloma); urinary tract obstruction; or sustained renal damage following an acute episode of ischemia or shock.
STAGES: Stage 1 CKD is defined as a GFR of less than 60 mL/min. As the GFR progressively drops (to 45mL/min, 30, 15 or 5 mL/min), the likelihood of complications of impaired renal functioning steadily increases. Stage 5 CKD is characterized by a GFR of approx. 5 mL/min. It is the threshold at which dialysis is necessary to maintain normal electrolyte and fluid balance.
SYMPTOMS AND SIGNS: Patients with Stage 1 CKD are typically asymptomatic. Patients who develop severe reductions in the ability of the kidneys to excrete water and toxins typically develop uremic symptoms, including anorexia, GI upset, and alterations in neurological function.
DIAGNOSIS: CKD is diagnosed with serial measurements of serum blood urea nitrogen (BUN) and chromium (Cr), and urinalyses. When serum creatinine rises suddenly, renal ultrasonography is used to determine whether the decline in kidney function has been caused by urinary tract obstruction (such as by prostatic hypertrophy or prostate cancer, or by kidney stones). Ultrasonography of the kidneys is also used to characterize their size. Small, shrunken kidneys are irreversibly diseased whereas the presence of multiple cysts identifies polycystic kidney disease. Enlargement of the renal pelvis may indicate hydronephrosis. Renal masses may suggest kidney cancer.
PREVENTION: General strategies that are employed to protect kidney function include: smoking cessation; optimal control of blood pressure and diabetes mellitus; limiting exposure to potential renal toxins; and the use of medications, such as angiotensin-converting enzyme inhibitors.
TREATMENT: Treatments depend on the underlying cause. Most patients with CKD need to control their dietary intake of fluids, salt, potassium, and foods that are rich in phosphorous. Excessive consumption ...