Reddish-brown distal nail bands with whitish, ground-glass appearance of the proximal parts is called as brown arcs or ‘half and half nails’. Half-and-half nails are characteristically seen in chronic renal failure.
It affects fingernails more often than toenails. No correlation exists between the severity of azotemia and the depth of the distal colour band. The band usually tends to remain unchanged even after dialysis but has been reported to disappear after successful renal transplantation. The pathogenesis of half-and-half nail is unclear. Estimates of prevalence among patients with chronic renal failure are reported as 15%-50%.
However, it must be noted that "idiopathic" half-and-half nails have also been reported in the literature.
You have not given much information on your "osteoporosis", the radiological findings, and serum calcium levels and other labs.Your serum phosphorus levels will be considered normal according to some laboratory reference ranges.But an isolated serum phosphorus level can not be used for diagnosis.
However, for the sake of discussion, i would like to mention a few possibilities for hyperphosphatemia.
Hypocalcemia and hyperphosphatemia with low/normal parathyroid hormone (PTH) levels can be observed in hypoparathyroidism (HP). This disorder may follow an autosomal dominant (AD) or autosomal recessive (AR) mode of inheritance. It can be idiopathic as well.
Similar biochemical changes may also be seen in pseudohypoparathyroidism (PHP) type Ia and Ib, but the affected individuals usually have elevated PTH levels indicative of PTH resistance. Features of Albright’s hereditary osteodystrophy (AHO) are typically not seen in patients affected by familial forms of PHP-Ib.
Hypomagnesemia also may be associated with hypocalcemia and may also cause hyperphosphatemia. Some examples are as follows.
- Late-onset glycogenosis type II with renal magnesium wasting, hypomagnesemic hypocalcemia, hypocalciuria and osteopenia.
- Gitelman syndrome (GS), also known as 'familial hypokalemia-hypomagnesemia', is an autosomal recessive salt-losing renal tubulopathy that manifestsis with hypomagnesemia, hypocalciuria and secondary aldosteronism, which is responsible for hypokalemia and metabolic alkalosis.
Prevalence of heterozygotes for this condition is approximately 1% in Caucasian populations.
Although it is not possible to offer any likely diagnoses based on the information given, i feel that you should have your serum magnesium levels checked.
MB BS, MS, FRCS(Edinburgh)