Clinical Scenario:
A 4-year-old boy is evaluated for progressive bowing of the legs and difficulty walking. He received two courses of therapeutic vitamin D over the past year with minimal improvement. His weight and height are both below the 3rd percentile. On examination, he has pallor, severe genu varum, widened wrists, muscle wasting, and a distended abdomen. His mother reports that he passes bulky, foul-smelling stools 3–4 times daily. Laboratory investigations show:
Hemoglobin: 8.2 g/dL
Serum calcium: 7.9 mg/dL
Serum phosphate: 2.7 mg/dL
Alkaline phosphatase: 1650 IU/L
Serum albumin: 2.8 g/dL
What is the most likely underlying diagnosis responsible for his rickets?
A. Celiac disease
B. Hereditary vitamin D–resistant rickets
C. Hypophosphatemic rickets
D. Nutritional vitamin D deficiency
E. Metaphyseal dysplasia
Correct answer & Explanation:
Correct Answer: A. Celiac disease
Discussion: Celiac disease
The key clues are:
Severe rickets not responding to vitamin D therapy
Failure to thrive
Pallor (iron deficiency anemia)
Hypoalbuminemia
Distended abdomen
Bulky, foul-smelling stools (steatorrhea)
These findings indicate chronic intestinal malabsorption, and the most likely cause is celiac disease.
The intestinal villous atrophy of celiac disease causes malabsorption of calcium and vitamin D, leading to secondary hyperparathyroidism and severe rickets. Iron deficiency anemia and hypoalbuminemia are additional clues suggesting malabsorption rather than isolated nutritional deficiency.
Why the other options are incorrect
B. Hereditary vitamin D–resistant rickets
Causes refractory rickets but does not explain steatorrhea, anemia, or hypoalbuminemia.
C. Hypophosphatemic rickets
Typically presents with short stature and lower-limb deformities.
Gastrointestinal symptoms and malnutrition are absent.
D. Nutritional vitamin D deficiency
Usually responds to appropriate vitamin D replacement.
Does not typically cause hypoalbuminemia and steatorrhea.
Key learning point:
In a child with refractory rickets, the combination of growth failure, iron deficiency anemia, hypoalbuminemia, and steatorrhea should immediately suggest celiac disease as the underlying diagnosis. Screening should begin with anti-tTG IgA antibodies and total serum IgA levels.
