Off Target But Hitting the Mark

On physical examination, she was distressed, writhing on the bed, and appearing comfortable only on her side with her knees flexed. Her temperature was 36.5 ° C, heart rate 83 beats per minute, respiratory rate 18 breaths per minute, blood pressure 143/77 mmHg, and oxygen saturation 94% while breathing ambient air. Her abdomen was diffusely tender, most markedly in the epigastrium. Abdominal rigidity, rebound tenderness, and costovertebral tenderness were absent. There was no rash; the previously reported targetoid skin lesion was no longer present. The remainder of the exam was normal.

Laboratory evaluation showed a white count of 7900/mm3, hemoglobin 14.3 gm/dL with normocytic indices, and a platelet count of 175,000/mm3. Sodium was 130 mmol/L, potassium was 3.1 mmol/L, bicarbonate 26 mmol/L, blood urea nitrogen 15 mg/dL, creatinine 0.6 mg/dL, and glucose 92 mg/dL. Serum calcium, aspartate aminotransferase, alanine aminotransferase, bilirubin, and lipase were normal. A urine pregnancy test was negative. Urine analysis was negative for nitrites and leukocyte esterase. Abdominal and pelvic computed tomography (CT) scan with intravenous (IV) contrast performed 3 days prior at an outside ED revealed a 3.4 centimeter left ovarian cyst. A subsequent transvaginal ultrasound was negative for cyst torsion and confirmed appropriate placement of an intrauterine device.

The absence of abdominal rigidity and rebound tenderness does not exclude peritonitis. A normal white blood cell count also does not reliably exclude serious intraabdominal pathology. However, the CT scan argues strongly against many common causes of abdominal pain, including appendicitis, diverticulitis, perforated ulcer, intestinal obstruction, and malignancy, assuming the symptoms have not changed since it was performed.

The patient’s laboratory studies argue against biliary obstruction, pancreatitis, pregnancy, hypercalcemia, and ongoing urinary tract infection. Patients with functional gallbladder disorders may have normal laboratory and CT findings but typically have recurrent, biliary-colic-type pain. The low serum potassium, a high blood urea nitrogen to creatinine ratio, and a low serum sodium reflect her significant vomiting. The hyponatremia is consistent with the appropriate release of antidiuretic hormone (ADH) in the setting of volume depletion. She should receive isotonic fluids plus potassium in addition to symptomatic treatment of pain and nausea. Given the severity and duration of symptoms, an esophagogastroduodenoscopy (EGD) should be performed to exclude GI mucosal disease, including peptic ulcer disease and gastritis, which may not be evident on the CT scan.

Additional diagnoses should be considered at this point. This patient has exposure to chickens, ducks, rabbits, and ticks as well as reported chills and mild temperature elevation at home. Tularemia, which can be transmitted by tick bites or exposure to infected rabbits, can cause a prolonged illness. Some patients have abdominal pain, anorexia, nausea, and weight loss, although fever is usually more prominent. Tularemia is uncommon and most frequently seen in the south-central part of the United States but has been reported throughout the country. She should be queried regarding additional exposures, including well water to assess her risk for Campylobacter infection.

Opiate withdrawal can present with pain and vomiting, but she reports no opiate use and lacks other findings such pupillary dilation or piloerection. Given the prevalence of opiate abuse, however, a toxicology screen should be performed. Hypercalcemia and diabetic ketoacidosis as metabolic causes of abdominal pain have been ruled out by her laboratory values. If no other cause is identified, other metabolic etiologies like Addison disease, familial Mediterranean fever, or porphyria should be considered.

Cyclic vomiting syndrome should still be on the differential. It is a diagnosis of exclusion requiring a history of recurrent, stereotypical episodes, which should be explicitly explored.

The patient was admitted to a medical unit by the hospitalist service and received IV normal saline, parenteral potassium, and IV pantoprazole. She underwent an EGD that revealed minor erosions in the antrum of the stomach. Biopsies were obtained.

Seven hours after the endoscopy, the patient had a brief period of confusion followed by a generalized tonic-clonic seizure lasting 1 minute. A head CT without contrast was negative for any focal abnormality. Repeat laboratory evaluation revealed that serum sodium was 125 mmol/L, and serum glucose was 113 mg/dL. She was transferred to the progressive care unit and received IV levetiracetam.

The endoscopy excluded structural abnormalities of the stomach and duodenum. The patient now has an additional problem, seizure, which needs to be incorporated in the diagnostic reasoning.

Seizures can be caused by the rapid development of severe hyponatremia, with serum sodium levels usually less than 120 mmol/L. Seizures caused by hyponatremia are typically preceded by headache and lethargy, as the intracellular movement of excess water causes cerebral edema. Hyponatremia is unlikely to be the cause of her seizure but should nevertheless be evaluated with a urine sodium concentration and serum and urine osmolality. If she is euvolemic, the IV fluids should be stopped and her free water intake should be restricted to avoid worsening the hyponatremia, as it is potentially caused by the syndrome of inappropriate ADH (SIADH).

There are many other possible causes for new onset seizures in adults, including brain tumor, head trauma, alcohol withdrawal, medications, and central nervous system infection, including Lyme disease. Lyme serologies should be repeated.

In this patient, it is likely that the seizure is a manifestation of the same illness that is causing her vomiting and abdominal pain. Seizure is not a feature of cyclic vomiting syndrome in adults. It is also not a feature of tularemia, adrenal insufficiency, or opioid withdrawal.

Acute intermittent porphyria (AIP) can cause both abdominal and neurologic problems. Hyponatremia is common during acute attacks, caused by either the inappropriate release of ADH or the appropriate release of the hormone if there is fluid loss. AIP is a rare diagnosis but could explain the uncommon combination of abdominal pain, vomiting, seizure, and hyponatremia. A spot urine porphobilinogen test should be sent to assess for AIP.