A 45-year-old woman comes to the clinic due to fatigue, weakness, and diffuse bone pain. She was diagnosed with celiac disease 5 years ago but continues to consume gluten-containing foods on occasion. The patient takes over-the-counter folic acid and iron supplements. Laboratory results are as follows: Which of the following is directly responsible for this patient's bone pain?

Question

A 45-year-old woman comes to the clinic due to fatigue, weakness, and diffuse bone pain.  She was diagnosed with celiac disease 5 years ago but continues to consume gluten-containing foods on occasion.  The patient takes over-the-counter folic acid and iron supplements.  Laboratory results are as follows:  Which of the following is directly responsible for this patient's bone pain?

Quizplus · Accepted Answer

Explanation: 11ec25c8_d0c7_bb21_bc81_f5923de40085_MD0003_00 This patient has osteomalacia, presenting with fatigue, bone pain, and hypophosphatemia. Osteomalacia is a potential complication of vitamin D deficiency and is frequently seen in patients with malabsorptive disorders (eg, celiac disease). In addition to bone pain, manifestations may include muscle weakness, a waddling gait, and increased risk of fracture. Bone density is typically decreased, and x-ray may reveal linear Looser zones. Looser zones 1,25-dihydroxyvitamin D is required for optimal intestinal absorption of calcium and phosphorus. In vitamin D deficiency, intestinal calcium absorption is impaired, leading to a series of metabolic alterations: 1,25-dihydroxyvitamin D intestinal calcium absorption is impaired Secretion of parathyroid hormone (PTH) is increased (ie, secondary hyperparathyroidism) to maintain circulating calcium levels. PTH causes release of calcium from bone stores, increases renal calcium reabsorption, and suppresses renal phosphate reabsorption. As a result, circulating calcium levels can be restored to normal or near normal, but phosphate levels are reduced (as in this patient). During new bone formation and remodeling, osteoclasts create a cavity at the bone surface that osteoblasts fill with organic matrix (osteoid). Calcium and inorganic phosphate then deposit in the matrix to mineralize the newly formed bone. However, calcium or phosphorus deficiency at the mineralization front will lead to reduced mineralization of the osteoid matrix. bone formation and remodeling (Choice A) Paget disease of bone is characterized by accelerated focal bone remodeling. It starts with increased osteoclastic activity, followed by rapid and disorganized new bone formation. Alkaline phosphatase is elevated (indicating increased osteoblast activity). However, serum calcium, phosphorus, and PTH levels are typically normal. (Choice B) Osteogenesis imperfecta is due to defective formation of type 1 collagen, which is required for development of bone, tendons, ligaments, skin, teeth, and sclera. It typically presents in childhood with fragility fractures, and additional manifestations (eg, short stature, impaired hearing, blue sclera) are often present. (Choice D) Osteoporosis is characterized by low bone mass, but the bone usually has adequate mineralization. Laboratory evaluation shows normal serum calcium, phosphorus, PTH, and alkaline phosphatase. (Choice E) Lytic bone lesions are due to malignant cell infiltration by solid tumors (eg, breast, renal cell) or multiple myeloma, which induce activation of osteoclasts and local destruction of bone. Due to the release of bone mineral, hypercalcemia is common, and PTH will be suppressed. Educational objective: Osteomalacia is due to defective mineralization of bone matrix. It is most commonly due to vitamin D deficiency, which leads to decreased intestinal calcium and phosphorus absorption with resultant secondary hyperparathyroidism. Clinical features include bone pain, muscle weakness, hypophosphatemia, and increased risk of fracture. References: Vitamin D deficiency in adults: when to test and how to treat. (http://www.ncbi.nlm.nih.gov/pubmed/20675513) Vitamin D deficiency presenting like hypophosphatemic osteomalacia. (http://www.ncbi.nlm.nih.gov/pubmed/23565447)

A 45-Year-Old Woman Comes to the Clinic Due to Fatigue