Fact or fib? renin-angiotensin-aldosterone system, appendicitis, and glaucoma
Vol.20, No.02, March 2012

Some of the clinical statements below are true, and some are not. Can you distinguish the facts from the fibs on the renin-angiotensin-aldosterone system, appendicitis and glaucoma?

1. The renin-angiotensin-aldosterone system

True / False

a) Renin is secreted by the kidneys.

b) Renin creates angiotensin I by converting angiotensinogen, which is released by the pancreas.

c) This is converted to angiotensin II by angiotensin converting enzyme (ACE), which originates in the liver.

d) Angiotensin II stimulates secretion of aldosterone from the adrenal cortex.

e) Angiotensin II is also a powerful vasoconstrictor, increasing blood pressure.

f) Aldosterone decreases renal reabsorption of water and sodium into the blood, decreasing fluid volume and lowering blood pressure.

g) ACE inhibitors tend to increase levels of bradykinin, a vasodilator produced by the kinin-kallikrein system, which helps lower blood pressure but is blamed for the side effects of dry cough and angioedema.

 

2. Appendicitis

True / False

a) The number one cause of acute appendicitis is blockage of the lumen of the appendix by fecalith (also known as appendicolith), a calcified fecal deposit.

b) In recent immigrants, the leading cause of obstruction is intestinal parasites.

c) Rebound abdominal tenderness is a highly specific sign of appendicitis.

d) Urine test is obligatory in a premenopausal woman with apparent symptoms of appendicitis.

e) Classic appendicitis begins as central abdominal pain before migrating to lower right fossa.

f) Elevated rates of appendicitis have been shown in patients who later developed colon and rectal cancer.

g) Patients with appendicitis have been shown to have lower fibre intake and longer intervals between stools.

h) There are scoring systems to help differentiate likely cases, unlikely cases, and equivocal cases needing imaging studies. The best-known is the Alamagordo scale.

 

3. Glaucoma

True / False

a) Glaucoma is the second-leading cause of blindness worldwide.

b) Glaucoma is the second-leading cause of blindness in Canada.

c) Caffeine is a risk factor for glaucoma, increasing intraocular pressure in healthy individuals.

d) People of African descent are at higher than average risk of open angle glaucoma.

e) People of East Asian are at higher risk of angle closure glaucoma.

f) In women, glaucoma is more likely than in men to involve angle closure.

g) Most cases of glaucoma in women are angle closure glaucoma.

h) Most cases of glaucoma in Inuit are angle closure glaucoma.

i) Eyedrop glaucoma medications can cause systemic interactions and effects, including sulfa allergy and bronchoconstriction.

ANSWER

1. The renin-angiotensin-aldosterone system. a) True; b) False, angiotensin I comes from the liver; c) False, ACE was thought to originate in the lungs, but new evidence suggests it’s native to vascular endothelial cells; d) True; e) True; f) False, aldosterone increases renal reabsorption, increasing fluid volume and further increasing blood pressure. g) True.

2. Appendicitis. a) True; b) False, it’s still fecalith blockage; c) False, rebound tenderness reflects inflammation of the peritoneum, and is common in all cases of peritonitis, whatever the cause; d) True, pregnancy and ectopic pregnancy absolutely must be ruled out; e) True; f) True; g) True; h) False, it’s the Alvarado scale.

3. Glaucoma. a) True, after cataracts; b) True, after macular degeneration; c) False, it’s only been shown to raise IOP in glaucomatous eyes, not normal eyes; d) True; e) True, due to shallower anterior chamber; f) True, for the same reason; g) False, open angle still accounts for more overall cases; h) True; i) True, with carbonic anhydrase inhibitors and beta-blockers respectively.

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