Fact or Fib ? Kidney function, statins and the parathyroid
Vol.19, No.09, December 2011

This quiz is just for fun. Some of the clinical statements below are true, and some are just us pulling your leg. See if you can distinguish the facts from the fibs on kidney function testing, statin side effects and parathyroid disorders.

1. Kidney function testing

True / False

a) A patient’s creatinine clearance number (CCr) is typically close to the glomerular filtration rate (GFR) but fractionally lower.

b) One common method for calculating estimated glomerular filtration rate (eGFR) is the Cockcroft-Gault formula.

c) One common method for calculating estimated glomerular filtration rate (eGFR) is the Modification of Diet in Renal Disease (MDRD) formula.

d) The most accurate method is the CKD-EPI formula.

e) CKD-EPI is particularly accurate when GFR is below 60 mL/min/1.73m2.

f) Children’s eGFR is estimated using the Weiss formula.

g) Normal kidney function is defined by a GFR above 60 mL/min/1.73m2 with no proteinuria.

h) Typical GFR in infants is about 110 mL/min/1.73m2.

 

2. Statin side effects

True / False

a) Adverse effects most commonly linked to statins are myalgias and reduced liver enzymes.

b) Liver enzymes often return to normal over time even without discontinuing the statin.

c) The largest current study suggests rhabdomyolysis risk on current statin therapy is 0.44 cases per 10,000 patient-years.

d) Cerivastatin (Baycol) was withdrawn in 2001 because post-approval rhabdomyolysis cases were nearly 10 times more frequent than other statins.

e) Adding niacin or a fibrate to a statin increases rhabdomyolysis risk almost tenfold.

f) Coenzyme Q10 supplements are sometimes used to treat statin-associated myopathy.

g) Grapefruit or grapefruit juice inhibit the metabolism of statins, dramatically reducing their potency.

 

3. Parathyroid disorders

True / False

a) Normal range for PTH is 50-120 pg/ml.

b) Parathyroid hormone increases serum concentration of calcium.

c) It decreases plasma phosphate levels, and increases intestinal production of vitamin D.

d) The parathyroid gland is located in the brainstem.

e) The leading cause of primary hyperparathyroidism is parathyroid gland adenoma.

f) The leading cause of secondary hyperparathyroidism is vitamin D deficiency.

g) Hypoparathyroidism is usually attributed to either autoimmune disease or accidental surgical damage to the gland.

h) Malignant tumours do not arise in parathyroid glandular tissue.

ANSWER

1. Kidney function testing: a) False, CCr is typically close to GFR but slightly higher; b) false, Cockcroft-Gault calculates CCr, not GFR; c) true; d) true; e) false, it’s superiority is greatest when kidney function is good, not poor; f) false, it’s the Schwarz formula; g) false, normal function is above 90 mL/min/1.73m2 with no proteinuria, though many nephrologists would like to lower that threshhold; h) true.

2. Statin side effects: a) False, myalgias and increased liver enzymes; b) true; c) true; d) true; e) true; f) true, though evidence of efficacy is lacking; g) false, grapefruit inhibits statin metabolism, thus potentiating statins’ effects.

3. Parathyroid disorders: a) False, normal range is 10-60 pg/ml; b) true; c) true; d) false, there are four parathyroid glands, and they surround the thyroid; e) true; f) false, it’s chronic kidney disease; g) true; h) false, they are rare but can occur.

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