Lab case 399 Interepretation

Question 1: 

PH = 7.43 that is with in normal range, more toward alkalotic spectrum

HCO3 = 39.9, that is elevated so we have metabolic alkalosis. Next we need to check the compensation process.

For metabolic alkalosis,  Expected pCO2 = 0.7 [HCO3] + 20 (range: +/- 5). Accordingly, expected pCO2 in this case = 0.7 x 39.9 + 20 (+/- 5) = 43 – 53. pCO2 in this case is 61 so we have an additional respiratory acidosis. (In this case we don’t have enough information to differentiate acute from chronic respiratory acidosis).

Other abnormal findings:

K+ = 2.4, that is severe hypokalaemia.

Cl =  Hypochloraemia

Question 2:

We use the mnemonic CLEVER PD for the differential diagnosis of metabolic alkalosis:

C – contraction (dehydration), possible

L – liquorice (diuretic), laxative abuse, excluded by history taking

E – endocrine (Conn’s, Cushing’s), unlikely.

V – vomiting, GI loss (villous adenoma), Patient has been vomiting.. most likely vomiting is the cause.

E – excess alkali (antacids), excluded by history taking

R – renal (Bartter’s). Unlikely

P – post hypercapnia, No

D – diuretics, excluded by history taking.


Question 3: 

This patient presented with vomiting for few days due to slipped lapband and she was dehydrated secondary to that.

Management is by IV hydration and K+ replacemet.

Consider Mg replacement, (mg deficiency enhance k loss).

Correction of the cause. (deflating or removing the lapband)