Diagnostic significance of reduced serum caeruloplasmin concentration in neurological disease

This study covers patients seen at a Wilson disease clinic between 1960 and 2002. The diagnosis of Wilson disease was confirmed in 316. Of 40 patients with a neurological presentation who were found not to have the disease, caeruloplasmin concentration was found to be reduced in 19. These 19 patients comprised 17 men and 2 women. The various diagnoses included Huntington's disease, multiple sclerosis, subacute sclerosing panencephalitis (SSPE), Hallervorden Spatz syndrome, and acaeruloplasminemia; in 9 no definite diagnosis was made. In view of the marked male preponderance, the lower limit of caeruloplasmin is calculated as for males. In an earlier study this was found to be 33.3 mg/dl (standard deviation, 6.1 mg/dl); therefore, 21.1 mg/dl is taken as the lower limit of normal. Particular attention is paid to 3 patients, 2 of whom had zero concentrations of caeruloplasmin and 1 had a very low level of the protein. Only 1 of these patients conformed to the classical picture of acaeruloplasminemia. The significance of a low caeruloplasmin concentration in patients with a variety of neurological syndromes is not clear but can lead to diagnostic confusion. When the concentration of this protein is very low or absent the diagnosis of acaeruloplasminemia must be considered.