[Two patients with renal medullary hyperechogenicity]

We report two patients with medullary nephrocalcinosis and nephrolithiasis. The first patients had unspecific symptoms of a systemic inflammatory disease, the second patient was asymptomatic.

Both patients had normocalcemia and normal parathyroid hormone levels, very high 1,25(OH)(2)-vitamin D and normal to low 25-OH-vitamin D levels. On renal ultrasound, both patients displayed nephrocalcinosis and nephrolithiasis.

Both patients showed dysregulation of the 1α-hydroxylase activity. The first patient suffered from a systemic inflammatory disease with consecutive activation of macrophages with extrarenal α-hydroxylase activity. The second patient had a "loss of function" mutation of the calcium sensing receptor with - for the situation - inadequatly high parathyroid hormone levels and consequently a renal dysregulation of the 1α-hydroxylase.

After immunosuppressive treatment with prednisolone and hydroxychloroquin there was complete remission of the systemic inflammatory disease in the first patient. In consequence the 1,25-(OH)(2)-vitamin D levels regressed and renal function stabilized. The second patient was completely asymptomatic with normal renal function, so far we did not initiate any treatment.

Nephrocalcinosis and nephrolithiasis can result from hypercalciuria due to dysregulated hydroxylation of vitamin D. For both renal and extrarenal sources causal treatment is available.