CASE #9
A 52-year-old woman with a history of congestive heart failure and recurrent urinary stones was evaluated in the emergency room because of chills and fever. Left flank pain had been present for 24 hours, and she has felt too sick to eat or drink. She self prescribed acetominophen and continued taking her furosemide, 40mg per day. On examination, the blood pressure was 80/50 mm Hg, the pulse was 120 and regular, the respiratory rate was 25 per minute, and the temperature was 40° C. There was marked tenderness over the left flank and left upper quadrant. Urinalysis disclosed a large number of leukocytes and a few white cell casts. Gram stain of unspun urine revealed gram-negative rods. On abdominal films, a 0.6 mm calcific density was seen in the region of the left ureterovesicular junction.
| LABORATORY RESULTS | |||
| TEST | RESULT | REFERENCE INTERVAL | |
| SERUM CHEMISTRY | |||
| SODIUM | 135 | 135-145 mEq/L | |
| POTASSIUM | 2.9 | 3.3-5.0 mEq/L | |
| CHLORIDE | 104 | 95-110 mEq/L | |
| BICARBONATE | 24 | 23-28 mEq/L | |
| UREA NITROGEN | 39 | 8-22 mg/dL | |
| CREATININE | 1.1 | 0.5-1.3 mg/dL | |
| ARTERIAL BLOOD | |||
| P02 | 108 | 75-100 mmHg | |
| PC02 | 22 | 38-45 mmHg | |
| pH | 7.65 | 7.38-7.44 | |
| URINE | |||
| Na | 40 meq/L | ||
| K | 50 meq/L | ||
| Cl | 50 meq/L |
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Questions
1. Characterize the acid-base disturbance(s).
Resp. Alkalosis with Metabolic Alkalosis
2. What is its most likely cause?
Resp alkalosis: sepsis, pain
Metabolic alkalosis: furosemide use with volume depletion: neither volume depletion nor hypokalemia alone usually results in metabolic alkalosis, but the combination often does, providing a potent stimulus for intercalated cell proton secretion.
3. Why is the serum potassium concentration low and the urine potassium high?
a. diuretic use
b. alkalosis
c. volume depletion with stimulated aldosterone
4. Why are there significant amounts of Na and Cl in the urine, despite volume depletion?
The action of fursemide on the thick ascending limb will often keep urine Na and Cl high, despite proximal reabsorption: therefore a "chloride responsive" alkalosis such as this may not present with a low urine chloride!
5. How would you treat the patient's acid-base disturbances?
Metabolic alkalosis: Normal saline, stop diuretic, give potassium
Resp alk: treat pain and infection