Rickets due to low Phosphorous (Hypophosphatemic Rickets): in Children When to Suspect ?

Rickets is a condition of the bone causing it to soften and weaken in children, usually because of an extreme and prolonged vitamin D deficiency, low Calcium or Phosphorous.

Q1) How does Phosphorous cause Rickets ?
A1) Calcium, Phosphorous and Vitamin D are the most important vitamins and minerals needed for adequate mineralization to make the bones strong. Any deficiency of any of these three can result in defective mineralization leading to weak bones and rickets. A condition due to low phosphorous in our body can result in Hypophosphatemic Rickets.

Q2) What causes Hypophosphatemic Rickets?
A2) Hypophosphatemic rickets is one of the most common type of refractory rickets in Indian children. Most of the hypophosphatemic disorders are inherited, though they may rarely be acquired due to underlying medical conditions like hyperparathyroidism, Fanconi Syndrome.
X-linked hypophosphatemic (XLH) rickets is the most common cause of heritable rickets and accounts for more than 80% of familial hypophosphatemic rickets. It occurs due to inactivating mutations in PHEX gene.

Q3) What are the signs and symptoms of Hypophosphatemic Rickets?
A3) The usual finding is frontal bossing which may appear as early as 6 months of age. As the child starts walking, limb deformities becomes more evident leading to disproportionate short stature with short limbs. Lower limbs are more affected leading bow legs or knock knees. Dental abnormalities are common like abscessed noncarious teeth, enamel defects, enlarged pulp chambers. Other features are short stature, bone pains, pseudofractures.

Q4) How do you diagnose Hypophosphatemic Rickets?
A4) Hypophosphatemic Rickets can be diagnosed by blood tests and X rays. Blood tests comprising serum phosphorus, calcium, elevated PTH, and TMP/GFR.

Q5) How is Hypophosphatemic Rickets managed ?
A5) Hypophosphatemic Rickets is diagnosed on the basis of history, examination and biochemical parameters. Treatment is correction of low phosphate levels in the body by oral supplements. Along with it Vitamin D and Calcium are also kept in the normal range.

Q6) What improvement can we except once treatment is started?
A6) On treatment the first sign to improve is the bone pains. The child runs and plays better. The biochemical markers improve within a. few weeks of treatment. The last parameter to improve is the bowing of legs. With proper treatment the height velocity also improves and helps children attain their proper growth potential.