Laxative Abuse
Physiology
- GI loss of bicarbonate -> hypovolemia with decreased sodium delivery to distal nephron
- Serum bicarbonate is replaced with chloride -> hyperchloremia
Diagnosis
- Serum Potassium: usually decreased
- Urine AG: (urine Na+ + urine K+) – (urine Cl-)
- Normal: -20 to -50 mEq/L
- Negative: urine AG becomes more negative (usually >-50 mEq/L), due to the kidney increasing H+ excretion in the form of NH4+