Background: Contraction
alkalosis is characterized by low serum
sodium and
chloride and high serum
carbon dioxide and
bicarbonate levels. Case Report: A 28-year-old Caucasian active-duty male with a history of
autosomal dominant polycystic kidney disease and
diarrhea-predominant
Irritable Bowel Syndrome (D-IBS) presented to his primary care provider (PCP) with elevated blood pressure (136/96 mmHg), was diagnosed with stage-2
hypertension, and started oral
HCTZ (25 mg/day). His medications included
dicyclomine (10 mg oral three times daily). Subsequently, (Visit 1), his blood pressure was 130/91 mmHg and he was started on
telmisartan (20 mg/day). At Visit 2, 4 weeks later, his blood pressure improved (121/73 mmHg); however, blood chemistry revealed elevated serum CO2 (32 mEq/L) and
chloride (94 mmol/L). Four days later, the patient presented to the Emergency Department with
dyspnea and swallowing difficulty. The patient returned to his PCP 3 days later complaining of
cough, congestion,
vomiting, and mild
dyspnea, blood pressure of 124/84 mmHg. Two months later, sudden onset of projectile
vomiting and
abdominal pain while running was reported, resolved by
rehydration and a single oral dose of
prochlorperazine 25 mg. Three months later, (Visit 3), he complained of
lightheadedness and cloudy judgment, suggesting contraction
alkalosis.
HCTZ was discontinued and
telmisartan was increased to 20 mg twice daily. A follow-up blood chemistry panel 2 weeks later revealed serum
chloride and CO2 levels within normal limits and blood pressure under 130/80 mmHg. Conclusion: This is the first known report of contraction
alkalosis driven by drug-drug interaction between
dicyclomine and
HCTZ.