High blood calcium levels

Fifteen per cent of patients with Williams syndrome have excessively high blood calcium levels, mainly at a very young age (hypercalcaemia). This can cause all kinds of abdominal discomfort and cause children to urinate frequently. In most cases, this hypercalcaemia disappears spontaneously after the second year of life.

There is evidence of a correlation with vitamin D metabolism, but the results of scientific studies are contradictory. The successful treatment of some patients with pamidronate, a drug that inhibits the excessive release of calcium from bone, indicates a dysregulation of vitamin D metabolism in these patients.

If the hypercalcaemia is present at a young age, a diet low in calcium is sometimes prescribed.