Laboratory Findings

Table 5 shows the characteristic laboratory findings in cases of MNK. The biochemical data most useful for diagnosis are low serum copper and ceruloplasmin levels. However, it should be noted that serum copper and ceruloplasmin levels are also very low in unaffected babies, especially in premature babies, and gradually increase to adult levels (Table 6) (44). In babies in whose cases MNK is suspected, therefore, serum copper and ceruloplasmin levels should be examined serially to determine whether the normally expected increase in copper and ceruloplasmin levels fails to appear. Serum copper and ceruloplasmin levels cannot be improved by oral administration of copper, but rise significantly after copper injection. Copper concentrations are significantly high in cultured fibro-blasts derived from these patients, and this is useful for diagnosis.

Fig. 4. A 14-yr-old patient with occipital horn syndrome. Mild muscle hypotonia is observed.

Abnormal catechol levels in the serum and cerebrospinal fluid are caused by a decrease in dopamine P-hydroxylase activity (10,45). The level of activity of lysyl oxidase, a key enzyme in the synthesis of the crosslinks in collagen, is also reduced, leading to connective tissue abnormalities. No biochemical markers for evaluating the connective tissue abnormalities have been reported. However, we examined the level of deoxypyridinoline, a degradation product of collagen, in the urine of 10 patients with MNK, and it was found to be significantly lower than the normal level (unpublished data). Based on these findings, it seems possible that the urine deoxypyridinoline level may be a useful marker for evaluating the connective tissue abnormalities in patients with MNK.

Copper accumulates significantly in the cells of the proximal tubules of the kidney. In three patients with MNK given copper injections, the urinary p2-microglobulin level was found to be significantly high, but amino aciduria, proteinuria, glucosuria, or hematuria was not observed (unpublished data). These results suggest that the accumulation of copper produces only a slight disturbance in renal function.

In patients with OHS, serum copper and ceruloplasmin levels are usually low. In some patients with OHS, however, normal levels of serum copper and ceruloplasmin have been reported (23,46,47). These findings indicate that a diagnosis of OHS cannot be excluded on the basis of normal serum

Fig. 5. Occipital horns (arrow) in a 14-yr-old patient with occipital horn syndrome.

Table 5

Laboratory Findings for Patients with Menkes Disease and OHS

Menkes disease Normal
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