Collagen metabolism in two types of autosomal dominant osteopetrosis during stimulation with thyroid hormones

In order to investigate collagen metabolism in two different types of autosomal dominant osteopetrosis (ADO), eight patients with type I (aged 23-61 years, mean 40.4 years) and nine patients with type II ADO (aged 20-49 years, mean 32.8 years) were compared with ten normal controls (aged 22-54 years, mean 35.4 years). The subjects were treated with 100 micrograms of triiodothyronine (T3) daily for 7 days and followed for a total of 4 weeks. Serum T3 increased in all subjects and a corresponding suppression of thyroid-stimulating hormone (TSH) was observed. Serum carboxy-terminal propeptide of type I collagen (S-PICP) in the control and type I groups showed no difference at baseline, whereas type II was lower than controls (p < 0.01). No significant alterations following stimulation were observed in any of the groups. Serum BGP (osteocalcin) values in the two patient groups were insignificantly lower than controls both at baseline and throughout the study. Following stimulation, a significant response was seen in the three groups (p < 0.001). The increases during the treatment period (delta values) for controls, type I and type II were 47.6% (p < 0.01), 51.7% (p = 0.05) and 34.8% (NS), respectively, with no difference between the groups. Serum bone-specific alkaline phosphatase (S-ALP) was not different between the groups and no alterations were observed in relation to treatment. The serum N-terminal propeptide of type III collagen (S-PIIINP) showed no difference at baseline between type I and controls but was significantly higher (p < 0.003) in type II than in the controls.(ABSTRACT TRUNCATED AT 250 WORDS)