A hidden cause of hypokalemia

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Figure 1
Algorithm for conducting a workup and differential diagnosis of metabolic alkalosis.
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Figure 2
Magnetic resonance imaging of the brain showed a 5-mm pituitary adenoma.
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Figure 3
Left lung perihilar nodule (blue circles) revealed by gallium-68 dotatate positron emission tomography.

TABLE 1

The patient’s initial laboratory test results

Laboratory test (reference range)	Results^a
White blood cell count (4.0–11.2 × 10⁹/L)	11.53
Hemoglobin (12.5–15.9 g/dL)	16.7
Platelet count (130–380 × 10⁹/L)	136
Sodium (136–145 mmol/L)	143
Potassium (3.5–5.1 mmol/L)	2.5
Chloride (98–107 mmol/L)	99
Bicarbonate (22–29 mmol/L)	34
Glucose (70–99 mg/dL)	127
Creatinine (0.67–1.17 mg/dL)	0.77
Blood urea nitrogen (6–23 mg/dL)	15
Calcium (8.6–10.2 mg/dL)	9
Albumin (3.5–5.2 g/dL)	4.2
Alanine aminotransferase (5–41 U/L)	61
Aspartate aminotransferase (5–40 U/L)	22
Alkaline phosphatase (40–129 U/L)	66
Bilirubin, total (0.2–1.2 mg/dL)	0.6
Arterial blood gasses
pH (7.35–7.45)	7.55
Partial pressure of carbon dioxide (35–50 mm Hg)	42
Partial pressure of oxygen (75–100 mm Hg)	97

TABLE 2

Urine studies

Laboratory test (reference range)	Results^a
Urine potassium, random (11–80 mmol/L)	27
Urine chloride, random (30–260 mmol/L)	35
Urine creatinine, random (40–279 mg/dL)	62
Urine potassium, 24-hour (25–125 mmol/24 hours)	275

TABLE 3

Cortisol hormone studies

Tests (reference range)	Results^a
Cortisol, morning level (2.7–18.4 μg/dL)	49.5
Urinary cortisol excretion, 24-hour (< 32 μg/24 hours)	5,904.8
Adrenocorticotropic hormone (7.2–63.3 pg/mL)	258