A 44-year-old woman with celiac disease comes to the physician with complaints of bone pain in her lower back and extremities. She followed a gluten-free diet for the first 5 years after diagnosis but has not done so for the last 2 years. The patient has 2 or 3 loose bowel movements a day. She also complains of weakness and low energy.
Physical examination shows no bony deformities. Her conjunctivae are pale. There is no organomegaly, and the remainder of the examination is unremarkable.
Which of the following is the most likely finding in this patient's initial laboratory workup?

Question

A 44-year-old woman with celiac disease comes to the physician with complaints of bone pain in her lower back and extremities.  She followed a gluten-free diet for the first 5 years after diagnosis but has not done so for the last 2 years.  The patient has 2 or 3 loose bowel movements a day.  She also complains of weakness and low energy.
Physical examination shows no bony deformities.  Her conjunctivae are pale.  There is no organomegaly, and the remainder of the examination is unremarkable.
Which of the following is the most likely finding in this patient's initial laboratory workup?

Quizplus · Accepted Answer

11ec193a_97ca_2ea6_853d_5fbe2cd01108_MD0002_00 Uncontrolled celiac disease results in decreased gastrointestinal vitamin D absorption and subsequent vitamin D deficiency. This leads to hypocalcemia and secondary hyperparathyroidism with elevated parathyroid hormone (PTH) levels. PTH causes increased bone resorption and turnover, which increases serum alkaline phosphatase. PTH also decreases urinary calcium excretion and increases urinary phosphate excretion, which normalizes serum calcium but lowers serum phosphate. Prolonged vitamin D deficiency leads to osteomalacia, inaccessible calcium stores in bone (unmineralized osteoid), and eventual hypocalcemia. Patients may develop pseudofractures, bone pain, or deformity. However, many patients can be asymptomatic with just the laboratory abnormalities. Thus, dual-energy x-ray absorptiometry scan is recommended for all patients with celiac disease for evaluation of bone loss. A gluten-free diet can partially reverse bone loss in some patients. (Choice B) These findings are suggestive of pseudohypoparathyroidism, in which there is resistance to the action of PTH, resulting in high PTH, high phosphorus, and low calcium. (Choice C) Low calcium, low PTH, high phosphorus, and normal alkaline phosphatase are seen in hypoparathyroidism. (Choice D) Renal osteodystrophy causes secondary hyperparathyroidism which leads to high PTH, low normal calcium, high alkaline phosphatase, and high phosphorus. Secondary hyperparathyroidism due to vitamin D deficiency causes low phosphorus. (Choice E) Primary hyperparathyroidism results in high calcium with high PTH. Phosphorus levels are usually low due to decreased renal tubular phosphate reabsorption, and alkaline phosphatase levels may be high in these patients. Educational objective: Metabolic bone disease (decreased bone mineral density and osteoporosis) can occur in celiac disease without significant gastrointestinal symptoms. Vitamin D deficiency due to malabsorption leads to secondary hyperparathyroidism and increased bone turnover. Dual-energy x-ray absorptiometry scan is recommended for all patients with celiac disease for evaluation and treatment of bone loss. __________ References: Evaluation and management of skeletal health in celiac disease: position statement. (http://www.ncbi.nlm.nih.gov/pubmed/23166906)

A 44-Year-Old Woman with Celiac Disease Comes to the Physician