Quiz 3

(Ref: Harrison 20th edition, page 316)
 The first two choices are eliminated as pH is normal.
 CKD leads to metabolic acidosis while vomiting leads to metabolic alkalosis.
 The key to the answer is anion gap which is elevated to 45 implying unmeasured anions. (Normal average of 10 meq).
 It points to mixed etiology of metabolic acidosis and alkalosis.
 Normal values of pH, pCO2 and HCO3 does not ensure absence of acid base imbalance.

(Ref: Harrison 19th edition, page 317)
 The pH shows acidosis and HCO, is low indicating the primary derangement as metabolic acidosis. The patient will compensate with respiratory alkalosis.
 To check for compensation, winter's formula is applied =1.5 x (HCO3) + 8 ± 2 = 1.5 x 9 + 8 ± 2 = 21.5 ± 2
 Since the value of pCO2 of the patient is as per the calculation, patient is having partially compensated metabolic acidosis.
 If the value of pCO2 was less than 19.5 or more than 23.5, then mixed disorder would have been present.

(Ref: Harrison 19th p 321)
 In kidney tubules H+ is lost as NH4 (positive charges) in 1:1 ratio with chloride (negative charges) in urine. To maintain electroneutrality positive and negative charges are lost equally.
 In all renal disorders (tubular or glomerular) metabolic acidosis ensues because loss of protons as NH4+ is impaired. Hence Chloride which is lost with NH4+ to maintain electroneutrality is also less lost.
 The build of H+ explains acidosis and Chloride build-up explains Hyperchloremia.
 In diarrhea HCO3 loss in stool leads to loss of negative charges from body. Hence the kidney preserves the negative charges leading to hyperchloremic metabolic acidosis
 Gitelman syndrome leads to salt loss and water loss from the body. The resultant dehydration triggers the R.A.S system leading secondary aldosteronism and development of metabolic alkalosis.

(Ref: Harrison 19th ed. / 479e-2)
Heavy sweating causes heat cramps, especially when the water is replaced without also replacing salt or potassium

(Ref: Harrison 19th ed. / 1750)
 In road traffic accident case there can be poly-trauma which can damage the spine as well. The damage to thoracic spine can destroy the sympatho-mimetic outflow to the heart causing bradycardia with hypotension. In this question if
tachycardia was given with hypotension, the answer would be hypovoleinic shock secondary to damage to organs like liver and spleen.

(Ref: Harrison 19th p 306, 307)
 In vomiting since the patient is developing dehydration the resultant R.A.A.S stimulation leads to increase of aldosterone and metabolic alkalosis ensues.
 Loss of hydrochloric acid in vomiting leads to kidney to conserve chloride leading to low urinary chloride.
 In Bartter syndrome, TAL is defective and promotes chloride loss. In Gitelman DCT is defective and promotes chloride loss. Since thiazides act on DCT, they have same effect as Gitelman syndrome.