Patient Care Endocrinology & Cardiology - December 2007 - (Page 25)

Case Comment Medical mysteries to sharpen your diagnostic skills & A 97-year-old woman with mental changes and polyuria I Case A 97-year-old African-American female nursing home resident is admitted for mental status changes, decreased oral intake, dehydration, and hypotension. She was being treated in the nursing home for a urinary tract infection and is on day 2 of amoxicillin/clavulanic acid therapy. On admission, she is awake but confused and incoherent. The nurse reports no recent history of fever, cough, nausea, vomiting, or diarrhea. The patient’s BP is 88/56 mm Hg; she is afebrile and weighs 143 lb (65 kg). Physical examination reveals dry skin and mucous membranes, clear breath sounds, regular heart rate and rhythm with a grade 3/6 systolic ejection murmur, a well-healed right mastectomy scar, a patent colostomy with pink stoma, good bowel sounds, and +1 bipedal edema with mild venous stasis discoloration bilaterally. Her past medical history is positive for type 2 diabetes mellitus, hypertension, hypothyroidism, gastroesophageal reflux disease, deep venous thrombosis, degenerative joint disease, right breast cancer (status postmastectomy), uterine and cervical cancers (status post-total hysterectomy with radiation therapy, colectomy with colostomy for radiation-induced colitis), depression, incontinence, and constipation. Her current medications include lisinopril, furosemide, levothyroxine, pantoprazole, warfarin, acetaminophen, sertraline, oxybutynin, and docusate sodium/ standardized senna concentrate (Senna-S). Initial laboratory tests reveal prerenal insufficiency (BUN, 43 mg/dL; creatinine, 1.4 mg/dL), nonanion gap hyperchloremic metabolic acidosis (chloride, 120 mEq/L; carbon dioxide, 8 mEq/L; anion gap, 8 mEq/L; pH 7.149), and leukocytosis (18,000 cells/ L). The urine culture grows Escherichia coli sensitive to nitrofurantoin and ceftriaxone; the blood culture is negative; and the international normalized ratio (INR) is 5.4.1 The chest x-ray and the rest of the metabolic panel are within normal limits. CT scan of the head reveals atrophy, small vessel disease, and a subacute infarction in the right basal ganglia. With IV fluids and the appropriate antibiotic, the patient’s BUN, creatinine, and WBC count are normalized, but she continues to be confused, anorexic, weak, and acidotic. Her diuresis is quite noticeable; she is voiding 2 to 3 L/d with a 1.5- to 2.5-L negative balance. • What other test results would you want to know? • What is the diagnosis, and how should this patient be treated? I Comment Serum osmolality, urine osmolality, urine sodium, and urine potassium were obtained at baseline, 4 hours after water deprivation, and 30 and 60 minutes after desmopressin acetate (DDAVP) injection. Urine osmolality ( 200 mOsm/kg at baseline) and urine electrolytes were found to be low. These results, in the presence of polyuria (50 mL/kg), were consistent with a diagnosis of diabetes insipidus (DI). In addition, the patient’s urine osmolality remained less than the plasma osmolality after a water deprivation test, and the urine osmolality increased by more than 50% after desmopressin injection. These findings were consistent with central DI. The patient was started on desmopressin, 2 mcg IV (0.03 mcg/kg/d) each evening, with a very good clinical response (immediate improvement in blood pH, serum carbon dioxide, and chloride as well as in her appetite). Her mental status also improved, with the patient becoming more alert, oriented, and conversant. Two days after diagnosis and treatment, she was discharged to the nursing home on desmopressin, 10 mcg nasal spray, 2 sprays daily. I Discussion DI is a heterogeneous condition caused by the inability to conserve water and maintain an optimum free water level. This is a caused by a lack of secretion of vasopressin following excessive water intake (polydipsia) or kidney resistance to its action. As a result, the kidneys pass large amounts of dilute urine DECEMBER 2007 PATIENT CARE ENDOCRINOLOGY & CARDIOLOGY 25

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Patient Care Endocrinology & Cardiology - December 2007 Research Digest Contents Medicine in the News Options for Managing Diabetes: Three Types of Basal Insulin Therapy Using the New AHA Guidelines for Preventing Coronary Heart Disease in Women Cardiovascular and Metabolic Implications of Polycystic Ovary Syndrome Case & Comment Classified Advertising Clinical Clips

Patient Care Endocrinology & Cardiology - December 2007

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