Explain the pathophysiology of acute renal failure. Include prerenal, intrarenal, and postrenal causes:
Kidneys help perform several vital body functions. Among these are the regulation of electrolytes, maintenance of an appropriate acid-base balance, control of blood pressure, production of hormones such as calcitriol, renin, and erythropoietin, and regulation of blood cell production. Kidneys actively filter waste products from the blood and pass to the urinary system for removal, and also control reabsorption of water, amino acids, and glucose. Acute renal failure is when the kidney cannot perform any of these functions normally. A useful way of categorizing acute kidney failure ...view middle of the document...
Fortunately these tests tend to be relatively easy for a medical laboratory to perform and of limited invasiveness to patients focusing on tests aimed at measuring urea, creatinine, potassium, and other electrolytes. Testing typically involves monitoring the levels of these products over some time period.
Blood urea nitrogen (BUN) measures the amount of nitrogen in the blood from urea. Increasing levels of BUN indicate the kidney is not effectively removing urea from the body. Serum creatinine tests measures the level of creatinine in the blood. Creatine is produced at a steady rate from the muscles and increasing levels of creatine can indicate a loss of kidney function. However, serum creatinine tests can be prone to interference. Creatine clearance measures the amount of creatine in both the blood and urine to calculate the creatinine clearance (CrCl), which reflects the glomerular filtration rate (GFR), a measure of kidney functionality. Serum potassium in a measure of potassium levels in blood, which also reflects kidney functionality. Urinalysis measures a whole range of products in urine including elctrolytes, blood cells, and glucose.
After simple body fluid exams tests are designed to exam the structual functionality of the kidney. For simplicity of equipment, availability and limited impact to patient abdominal ultrasound is preferred. However, it is difficult to determine blockages in the urinary tract and abdominal x-ray, abdominal CT scan, and abdominal MRI may be used instead. More sophisticated blood tests include arterial blood gas and blood chemistry testing for determination of metabolic acidosis. A condition shown by heightened acid levels in the blood.
Progression of renal failure is generally categorized to three stages.
First stage – acute renal failure. Reduced kidney effectiveness in filtering out waste products and loss of control over blood chemistry show up as increasing creatine levels in blood and low urine production. Patients begin to experience drowsiness, headache, and backpain.
Second stage – chronic renal failure. Further loss of kidney function and constant elevated creatine/waste product levels begin to have more widespread impacts on patients. Symptoms advance to physical weakness, loss of appetite, loss of urinary control with frequent urination during nights, persistent hiccups, muscular twitching, some swelling from water retention, and metallic taste in the mouth. Tests show severe decreases in the kidney glomerular filtration rate.
Third stage – End with complete loss of kidney function. The patient must decide to choose between dialysis treatment, transplant, or in extreme cases of belief systems advocating no use of conventional medical treatments, death. The patient’s body begins to break down further from highly elevated levels of blood toxins and lack of urine production with advanced symptoms including swelling of face, limbs, and abdomen. Severe abdomen pain, furry...