4.1 of 49 Ratings
A mother brings her 4-year-old daughter to your clinic for evaluation of knocked knees and short stature. On exam, the patient ambulates with a circumduction gait pattern and frequently falls. Plain radiographs are displayed in Figure A. Laboratory data is obtained and notable for calcium 9.1 mg/dL (RR 8.5-10.2 mg/dL), phosphorus 2.9 mg/dL (RR 4.3-5.4 mg/dL), alkaline phosphatase 405 U/L (RR 169-372 U/L), 25-OH vitamin D 38 ng/mL (RR 25-50 ng/mL), 1,25-OH vitamin D 21 pg/mL (RR 24-86 pg/mL), PTH 25 pg/mL (RR 15-65 pg/mL). The child is adopted and family history is not known. Which is the most likely diagnosis?
Physiologic genu valgum
Familial hypophosphatemic rickets
Select Answer to see Preferred Response
Low serum phosphate and normal calcium levels are found in what common etiology of hereditary rickets?
Vitamin D-dependent, type I
Vitamin D-dependent, type II
Autosomal dominant hypophosphatemic
Jansen's metaphyseal chondrodysplasia
Laboratory values of a normal serum calcium and parathyroid hormone can be found in which of the following disease states?
Type I vitamin D deficient rickets
Type II vitamin D deficient rickets
X-linked hypophosphatemic rickets
You are seeing a 4-year-old girl for leg deformities on a mission trip to Haiti. Clinical photograph and radiographs of her lower extremities and wrist are shown in Figures A-C. What laboratory studies would help confirm a nutritional deficiency as opposed to an X-linked genetic disorder as a cause of her condition?
Low serum phosphate, elevated alkaline phosphatase, elevated PTH
Low serum phosphate, elevated alkaline phosphatase, normal PTH
Low serum phosphate, elevated alkaline phosphatase, decreased PTH
Elevated serum phosphate, elevated alkaline phosphatase, elevated PTH
Elevated serum phosphate, decreased alkaline phosphatase, decreased PTH
Loss of function in the 25(OH) vitamin D1-alpha hydroxylase gene causes which of the following diseases?
Vitamin D resistant rickets
Hereditary Vitamin D dependant rickets type I
Hereditary Vitamin D dependant rickets type II
Which of the following statements about Familial Hypophosphatemic Rickets (Vitamin D resistant Rickets) is TRUE?
It is the second most common form of heritable rickets behind Type I Hereditary Vitamin D-Dependent Rickets
It is caused by inability of renal tubules to absorb phosphate
Leads to decreased vertical physeal width
There is a associated hyperphosphatemia
Early treatment with calcitriol results in completely normal bone mineralization
Which of the following laboratory values would be consistent with nutritional rickets?
increased calcium level
increased phosphate level
decreased alkaline phosphatase level
increased vitamin D level
increased parathyroid hormone level
The active form of vitamin-D (calcitriol) is produced by the enzyme 1-alpha-hydroxylase. What hormone activates this enzyme?
thyroid stimulating hormone (TSH)
parathyroid hormone (PTH)