Snapshot A 6-year-old boy is brought to his pediatrician by his parents due to poor growth, weakness, and abnormal gait. On physical exam, there is bowing of the legs and tenderness upon palpation of the lower extremity. Laboratory testing is significant for a decreased serum calcium and phosphate levels and elevated parathyroid hormone and serum alkaline phosphatase levels. (Rickets secondary to vitamin D defiency) Introduction Clinical definition osteomalacia a condition due to defective mineralization of osteoid rickets a condition due to defective mineralization of cartilage in the epiphyseal growth plates Epidemiology Demographics children can have both osteomalacia and rickets adults can only have osteomalacia since their growth plates have been fused Risk factors vitamin D deficiency secondary to poor dietary intake and sun exposure malabsorption e.g., inflammatory bowel disease and gastrointestinal bypass surgery genetic causes that result in vitamin D deficiency and vitamin D resistance primary hypophosphatemia e.g., X-linked hypophosphatemic rickets and autosomal dominant hypophosphatemic rickets Etiology Vitamin D deficiency Hypophosphatemia Chronic kidney disease e.g., metabolic acidosis and decreased 1,25-dihydroxyvitamin D synthesis Renal tubular acidosis proximal (type II) renal tubular acidosis/Fanconi syndrome secondary to phosphate wasting, metabolic acidosis which increases calcium loss, and secondary hyperparathyroidism Inhibitors of bone mineralization e.g., bisphosphonates, alimunum, and fluoride Hypophosphatasia a tissue non-specific alkaline phosphatase (TNSALP) gene mutation that leads to the accumulation of pyrophosphate pyrophosphate inhibits bone mineralization Pathogenesis impaired mineralization of osteoid (osteomalacia) and/or cartilage at the epiphyseal plates (rickets) Presentation Symptoms bone and joint pain muscle weakness difficulty with walking fractures Physical exam pediatric bowed legs rachitic rosary line costochondral thickenings Harrison's groove depression along line of diaphragmatic insertion into rib cage kyphosis as well as lordosis and scoliosis poor growth bone tenderness to palpation Imaging Radiography indication perform in patients with a clinical presentation concerning for osteomalacia or rickets findings osteomalacia reduced bone mineral density a non-specific finding inability to radiologically distinguish vertebral body trabeculae the film appears poor quality Looser pseudofractures, fissues, or narrow radiolucent lines characteristic radiologic findings rickets perform an anteriorposterior radiograph in skeletal areas that are rapidly growing (e.g., knee or wrist) osteopenia metaphysis may appear frayed and widened distal physis may appear widened bones of the arms and legs may have angular defomities Studies Labs highly dependent on the cause e.g., patients with vitamin D deficiency will have decreased 25-hydroxyvitamin D Laboratory Abnormalities in Rickets/OsteomalaciaEtiologySerum PhosphateSerum CalciumSerum Alkaline PhosphataseParathydroid HormoneVitamin D deficiency Decreased or normal Decreased or normal Elevated ElevatedUrinary phosphate wasting Decreased Normal Elevated or normal NormalProximal (type II) renal tubular acidosis Decreased Normal Normal NormalHypophosphatasia Normal Normal Decreased Normal Differential Child abuse Osteogenesis imperfecta Osteoporosis Paget disease of bone Multiple myeloma Vitamin D resistant rickets normal vitamin D and normal PTH Laboratory Abnormalities in Select Bone DisordersEtiologySerum PhosphateSerum CalciumSerum Alkaline PhosphataseParathyroid HormoneOsteoporosisNormalNormal or decreasedNormalNormalPaget disease of the boneNormalNormalElevatedNormalOsteitis fibrosa cysticaPrimaryhyperparathyroidism •decreasedSecondaryhyperparathyroidism •increasedPrimaryhyperparathyroidism •increasedSecondaryhyperparathyroidism •decreasedPrimary and secondary hyperparathyroidism •increasedPrimary and secondary hyperparathyroidism •increasedHypervitaminosis DIncreasedIncreasedNormalDecreased Treatment Medical treatment is directed against the underlying cause for example vitamin D supplemention indication in patients with vitamin D deficiency hereditary hypophosphatemic rickets along with phosphate supplementation osteomalacia of renal tubular acidosis along with sodium or potassium citrate Complications Fractures Growth abnormalities Prognosis Depends on the etiology
QUESTIONS 1 of 3 1 2 3 Previous Next Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK (M2.OR.16.22) A 70-year-old woman presents to the office for a yearly physical. She states she has recently started experiencing pain in her legs and her back. Last year, she experienced a fracture of her left arm while trying to lift groceries. The patient states that she does not consume any dairy and does not go outside often because of the pain in her legs and back. Of note, she takes carbamazepine for seizures. On exam, her vitals are within normal limits. You suspect the patient might have osteomalacia. Testing for which of the following is the next best step to confirm your suspicion? QID: 104347 Type & Select Correct Answer 1 7-dehydrocholesterol 0% (0/10) 2 25-hydroxyvitamin D 40% (4/10) 3 1,25-hydroxyvitamin D 60% (6/10) 4 Pre-vitamin D3 0% (0/10) 5 Dietary vitamin D2 0% (0/10) M 6 Question Complexity E Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 2 Review Tested Concept Review Full Topic (M2.OR.14.17) A 2-year-old boy presents to the pediatrician for a well-child visit. The child has been doing well and this is his first visit to a pediatrician after being adopted. His parents state that he is doing well and wanted him to generally be checked out. His temperature is 97.0°F (36.1°C), blood pressure is 100/65 mm Hg, pulse is 100/min, respirations are 17/min, and oxygen saturation is 98% on room air. Physical exam is notable for the finding in Figure A. Laboratory values are ordered as seen below.Serum:Ca2+: 9.1 mg/dLPhosphorus: 1.1 mg/dLAlkaline phosphatase: 462 U/LParathyroid hormone: 23 pg/mL (N = 10-55)1,25-dihydroxyvitamin D: 22 pmol/L (N = 15-30)What is the most likely diagnosis? QID: 104464 FIGURES: A Type & Select Correct Answer 1 Pseudohypoparathyroidism 50% (17/34) 2 Renal osteodystrophy 15% (5/34) 3 Vitamin D deficiency rickets 6% (2/34) 4 Vitamin D resistant rickets 24% (8/34) 5 Type II vitamin D dependent rickets 3% (1/34) M 6 Question Complexity E Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 4 Review Tested Concept Review Full Topic
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