A white man, age 56, presented to his primary care clinician with wrist pain and swelling. Two days earlier, he had fallen from a step stool and landed on his right wrist. He treated the pain by resting, elevating his arm, applying ice, and taking ibuprofen 800 mg tid. He said he had lost strength in his hand and arm and was experiencing numbness and tingling in his right hand and fingers.
The patient’s medical history included hypertension, type 2 diabetes mellitus, morbid obesity, obstructive sleep apnea, asthma, carpel tunnel syndrome, and peripheral neuropathy. His surgical history was significant for duodenal switch gastric bypass surgery, performed eight years earlier, and his weight at the time of presentation was 200 lb; before his gastric bypass, he weighed 385 lb. Since the surgery, his hypertension, diabetes, asthma, and sleep apnea had all resolved. Table 1 shows a list of medications he was taking at the time of presentation.
The patient, a registered nurse, had been married for 30 years and had one child. He had quit smoking 15 years earlier, with a 43–pack-year smoking history. He reported social drinking but denied any recreational drug use. He was unaware of having any allergies to food or medication.
His vital signs on presentation were blood pressure, 110/75 mm Hg; heart rate, 53 beats/min; respiration, 18 breaths/min; O2 saturation, 97% on room air; and temperature, 97.5°F.
Physical exam revealed that the patient’s right wrist was ecchymotic and swollen with +1 pitting edema. The skin was warm and dry to the touch. Decreased range of motion was noted in the right wrist, compared with the left. Pain with point tenderness was noted at the right lateral wrist. Pulses were +3 with capillary refill of less than 3 seconds. The rest of the exam was unremarkable.
The differential diagnosis included fracture secondary to the fall, osteoporosis, osteopenia, osteomalacia, Paget’s disease, tumor, infection, and sprain or strain of the wrist. A wrist x-ray was ordered, as were the following baseline labs: complete blood count with differential (CBC), vitamin B12 and folate levels, blood chemistry, lipid profile, liver profile, total vitamin D, and sensitive thyroid-stimulating hormone. Test results are shown in Table 2.
X-ray of the wrist showed fracture only, making it possible to rule out Paget’s disease (ie, no patchy white areas noted in the bone) and tumor (no masses seen) as the immediate cause of fracture. Normal body temperature and normal white blood cell count eliminated the possibility of infection.
Because the patient was only 56 and had a history of bariatric surgery, further testing was pursued to investigate a cause for the weakened bone. Bone mineral density (BMD) testing revealed the following results:
• The lumbar spine in frontal projection measured 0.968 g/cm2 with a T-score of –2.2 and a Z-score of –2.2.
• Total BMD of the left hip was 0.863 g/cm2 with a T-score of –1.7 and a Z-score of –1.4.
• Total BMD of the left femoral neck was 0.863 g/cm2 with a T-score of 1.7 and a Z-score of –1.1.
These findings suggested osteopenia1,2 (not osteoporosis) in all sites, with a 12% decrease of BMD in the spine (suggesting increased risk for spinal fracture) and a 16.3% decrease of BMD in the hip since the patient’s most recent bone scan five years earlier (radiologist’s report). Other abnormal findings were elevated parathyroid hormone (PTH) serum, 95.7 pg/mL (reference range, 10 to 65 pg/mL); low total calcium serum, 8.7 mg/dL (reference range, 8.9 to 10.2 mg/dL), and low 25-hydroxyvitamin D total, 12.3 ng/mL (reference range, 25 to 80 ng/mL).
A 2010 clinical practice guideline from the Endocrine Society3 specifies that after malabsorptive surgery, vitamin D and calcium supplementation should be adjusted by a qualified medical professional, based on serum markers and measures of bone density. An endocrinologist who was consulted at the patient’s initial visit prescribed the following medications: vitamin D2, 50,000 U/wk PO; combined calcium citrate (vitamin D3) 500 IU with calcium 630 mg, 1 tab bid; and calcitriol 0.5 μg bid.
The patient’s final diagnosis was osteomalacia secondary to gastric bypass surgery. (See “Making the Diagnosis of Osteomalacia.”4-6)
DISCUSSION
According to 2008 data from the World Health Organization (WHO),7 1.4 billion persons older than 20 worldwide were overweight, and 200 million men and 300 million women were considered obese—meaning that one in every 10 adults worldwide is overweight or obese. In 2010, the WHO reports, 40 million children younger than 5 worldwide were considered overweight.7 Health care providers need to be prepared to care for the increasing number of patients who will undergo bariatric surgeries to treat obesity and its related comorbidities.8