Modifiable risk factors of osteoarthritis also appear to be significant determinants of tibial cartilage volume. Serum testosterone may provide one possible explanation for gender differences in tibial cartilage volume and prevalence of tibiofemoral osteoarthritis. The proposed link between osteoarthritis and knee cartilage volume and the effect of testosterone will need to be confirmed in longitudinal studies.

In most trials, at least 50% of patients with Graves' disease treated with antithyroid drugs (ATD) relapse after achieving euthyroidism. At present, there are no definitive prognostic parameters available early in treatment to indicate those likely to achieve long-term remission. Because thyrotropin receptor antibodies (TRAb) are specific for Graves' disease, the possibility that their rate of change early in treatment (0 to 6 months) might be such an indicator was explored. TRAb were measured both as thyrotropin binding inhibitory immunoglobulins (TBII) and as thyroid-stimulating antibodies (TSAb) in 85 patients with untreated Graves' disease at 6-month intervals throughout their ATD treatment. The patients in the study were treated for a minimum period of 12 months and were categorized retrospectively into two groups depending on whether or not they remained in remission after ATD treatment. Remission was deemed as reached in patients who remained euthyroid for a minimum period of 15 months after cessation of ATD. The mean initial TBII and TSAb values in the nonremission group were significantly higher than in the remission group (p < 0.001 for both parameters). The rates of fall in mean TBII levels were similar for each group in the first 6 months of treatment, but while they continued to fall in the remission group over the next 6 to 12 months, mean values for the nonremission group plateaued and failed to fall to control levels within that period. These results indicate that changes in TRAb levels, measured either as TBII or TSAb, occur more rapidly in the second 6 months of treatment in patients who ultimately achieve remission than those who do not. If TBII fall to control levels by 12 months, the patient has at least a 70% chance of ultimately achieving remission with ATD treatment alone.

The JPO9 cells provide similar diagnostic information to FRTL-5 cells in patients with autoimmune thyroid disease. However, because they are more sensitive, grow faster, have less fastidious growth requirements and respond to unextracted sera, compared to FRTL-5 cells, we conclude that the JPO9 cells are preferable for the measurement of TSAb.

Radioactive iodine (RAI)-induced changes in the levels of antibodies to the thyroid-stimulating hormone (TSH) re¬ ceptor (TRAb) in patients undergoing treatment for autoimmune thyroid disease have been well documented. Previous studies have reported effects on the overall level of the antibodies present, TSH-binding inhibitory im¬ munoglobulins (TBII), without detailed studies of specific effects on the levels of thyroid-stimulating (TSAb) or thy¬ roid-blocking antibodies (TBAb). More detailed studies have been reported only in individual cases. In this study, the values of TSAb, TBAb, and TBII were measured longitudinally in 33 patients (27 females and 6 males) who re¬ ceived RAI. The bioassays for TSAb and TBAb were performed in JP09 cells. Following RAI, there were signifi¬ cant and immediate effects on the values of TBII in 70% of patients. TBII levels fell in 7 patients (20%) (Group 1), rose in 16 patients (48%) (Group 2) or remained unchanged but elevated in 10 patients (32%) (Group 3). In the Group 1 patients, only TSAb were detectable and none of these patients became hypothyroid after treatment. In the 16 patients in Group 2, increases in TBII were attributable to specific increases in TSAb in 7 (44%), in TBAb in 3 (19%), and in both TSAb and TBAb in 3 (19%). There were 3 patients (19%) in this group in whom there was no detectable TSAb or TBAb activity despite the increase in TBII. Six patients from this group became hypothy¬ roid within 6 months of RAI treatment. In the 10 patients in Group 3, 5 patients (50%) were positive for TBAb only, 2 (20%) were TSAb-only positive, and 3 (30%) were both TSAb-and TBAb-positive. Five patients (50%) in this group became hypothyroid and all had TBAb present in their circulation. Our results show that there are di¬ verse changes in TBII, TSAb, and TBAb following RAI. Hypothyroidism occurred in 33% of the patients treated with RAI therapy and TBAb were present in 75% of these hypothyroid patients. When TBAb were present in the absence of TSAb, hypothyroidism occurred in 6 of 8 versus 3 of 14 where TSAb were present alone (p < 0.05). The development of hypothyroidism within 6 months of RAI treatment was not related to continuation or dosage of an¬ tithyroid drugs and was transient in 50% of patients. We conclude that early hypothyroidism following RAI ther¬ apy is associated with increased TBAb in some patients and that recognition of this clinical situation should avoid unnecessary life-long thyroxine replacement.

Osteoporosis in men is an emerging public health problem. As calcitriol reduces the rate of vertebral fractures in osteoporotic postmenopausal women, we conducted a prospective study of this treatment in men with primary osteoporosis. Our study was a 2-yr, randomized, double masked, double placebo-controlled trial of calcitriol (0.25 microg twice daily) or calcium (500 mg twice daily) in 41 men with primary osteoporosis and at least 1 baseline fragility fracture. Thirty-three men (85%) completed the study. There were no differences in baseline characteristics. Spinal and femoral neck bone mineral densities at 2 yr were unchanged in both groups. Serum osteocalcin decreased in both groups by 30% (P < 0.05), whereas urine N-telopeptide cross-links decreased only in the calcium group by 30% (P < 0.05). After 2 yr, fractional calcium absorption increased by 34% (P < 0.01) in the calcitriol group. Nineteen incident fragility fractures occurred (14 vertebral and 5 nonvertebral) in 7 men. Over 2 yr, the number of men with vertebral fractures (6 vs. 1; P = 0.097) was similar in both groups. In conclusion, the efficacy of calcitriol remains unproven as a single agent for the treatment of osteoporosis in men.