CCHT Exam Practice Questions
1. All of the following substances are produced by the kidney EXCEPT:
2. The most likely cause of post-renal failure is:
a. severe dehydration.
b. nephrotoxic drug.
d. benign prostatic hypertrophy.
d. polycystic kidney disease.
4. Uremia may cause which of the following conditions?
b. Edema (swelling) of the extremities
d. All of the above
5. All of following conditions are associated with chronic kidney failure EXCEPT:
a. low hemoglobin.
1. B: In addition to its role in water and electrolyte balance and acid-base control, the kidney also produces substances that are of importance in erythropoiesis, vitamin D metabolism, and blood pressure control. Production of the hormone erythropoietin by juxtaglomerular renal cells is important in controlling red blood cell production in the bone marrow. In the presence of anemia, the resulting hypoxia stimulates the hypoxia-inducible transcription factor in these cells, and increased amounts of erythropoietin are produced. A decrease in renal perfusion leads to increased production of renin by the kidney; this enzyme catalyzes the conversion of angiotensinogen to angiotensin 1, which is subsequently converted to angiotensin 2 by an angiotensin-converting enzyme. The latter stimulates aldosterone secretion by the adrenal gland. The renin-angiotensin-aldosterone system is of great importance in the regulation of blood pressure. The active form of vitamin D, calcitriol, is also produced in the kidney.
2. D: Acute renal failure (ARF) is usually classified by the anatomic location of the damage. Pre-renal failure typically is caused by hypotension, resulting from trauma, dehydration, or blood loss in which the renal blood flow is markedly diminished. Intrarenal failure is caused by intrinsic kidney diseases, such as glomerulonephritis or renal toxic drugs, such as certain antibiotics, chemotherapy agents, or radiologic contrast materials. Post-renal failure may be caused by problems distal to the kidney that cause obstruction to urine flow, such as ureteral calculi, kinked ureter, neoplastic invasion, or prostatic hypertrophy in men. ARF may proceed to chronic renal failure but may resolve with careful medical treatment and sometimes hemodialysis.
3. A: Diabetes mellitus is the commonest cause of chronic renal failure (CRF) in the United States. Because of the obesity epidemic, type 2 diabetes (90% of diabetic patients) is on the rise, and thus, there may be even more cases of CRF in the future. Diabetic nephropathy is most likely caused by endovascular damage to the renal vessels. Hypertension is the second leading cause of CRF. It is most often of the so-called essential type in which the exact cause is unknown. In the first few years of this decade, about 27% of patients on dialysis had kidney failure as a result of hypertension. Renal disease or renal artery stenosis may also cause hypertension with its deleterious effects. Additional causes of CRF include glomerular diseases and polycystic disease. Less common causes of CRF are cancer, kidney infections, AIDS, systemic lupus erythematosus, and sickle cell disease.
4. D: Uremia is the term given to a constellation of symptoms, resulting from kidney failure with a resultant buildup of waste products in the circulation (e.g., urea), Some of the typical symptoms include fatigue (often resulting from anemia, which is common in chronic renal disease), itching, myalgias, dyspnea or edema from fluid retention, skin pallor or yellowish cast, foamy urine (due to protein), and nocturia. Loss of protein in the urine greater than 3.5 g/d is referred to as the nephrotic syndrome and may be a cause of excessive fluid retention. Often these symptoms develop gradually so frequent inquiry of the patient is indicated. Hemodialysis may improve uremic symptoms, but it only reproduces about 15% of normal kidney function; thus, an increased frequency and duration of hemodialysis may be indicated if the symptoms persist.
5. B: Numerous abnormalities of the blood, protein, and electrolytes occur in chronic renal failure. Anemia is very common due to frequent blood loss with resulting iron deficiency and diminished secretion of erythropoietin by the diseased kidney. Calcium absorption is impaired due to inadequate calcitriol, and phosphate is not adequately excreted by the tubules, resulting in elevated phosphate levels. A low calcium level stimulates the parathyroid gland to produce more parathyroid hormone, producing so-called secondary hyperparathyroidism. This may result in calcium deposition in the heart and blood vessels. Elevated potassium levels are also quite common in these patients and may be life-threatening.