Markers of inflammation after zoledronic acid redosing.

The symptoms of acute phase response (APR) following the first infusion of zoledronic acid (ZA) are attenuated after re-administration. We investigated the reasons for this attenuation, focusing on the changes in several hormones, bone markers and markers of inflammation occurring after the second ZA injection in patients who had experienced a severe APR after their first ZA infusion. Twenty-two postmenopausal women with osteoporosis and severe symptoms of APR following the first ZA infusion were included in the study (group A1). A year later, the same women (possibly with a residual activity of ZA) were subjected to ZA re-administration (group A2). Urine NTx (uNTx), white blood cells, parathyroid hormone, serum calcium, phosphorus and several serum markers of inflammation were measured before (0) and at 1 and 2 days following the first as well as the second infusion. In group A1, the APR was associated with a significant increase in serum C-reactive protein (CRP), high-sensitive interleukin 6 (hsIL-6), high-sensitive tumor necrosis factor alpha (hsTNF-α) and cortisol within 24 h after the infusion. The majority of the patients in group A2 did not experience an APR and serum calcium, phosphorus, CRP, hsIL-6, hsTNF-α, and cortisol remained essentially unchanged throughout the study. In group A2, on day 0, the uNTx were significantly lower than in group A1. In group A1 the uNTx decreased by 69 and 78% from baseline on days 1 and 2, whereas in group A2, they decreased by 48 and 53% (p < 0.01), respectively. A positive correlation was found between the degree of uNTx decline from the baseline levels (Δ-uNTx) and hsTNF-α and between Δ-uNTx and CRP. The Δ-uNTx, reflecting the osteoclast-mediated bone resorption, may play some role in the APR appearance, although it must be excluded if the relationships of the changes between uNTx and hsTNF-α/CRP are coincidental effects and not causal.

Transient changes in thyroid functions tests after zoledronic acid infusion.

Zoledronic acid (ZA) induces an acute phase response in association with elevation of serum cytokines, which possibly alter the 3 types of iodothyronine deiodinase activity. We therefore studied the possible alteration in thyroid function tests by ZA. We investigated the acute changes in serum thyroid hormones, TSH, cortisol, white blood cells, CRP, interleukin-6 (IL-6) and tumor necrosis factor (TNF-α), before (0) and 1, 2 and 3 days after iv infusion of 5 mg ZA in 24 asymptomatic postmenopausal women with osteoporosis (ZA group) in comparison with a placebo group. In the majority of patients the ZA infusion was associated with acute phase response and fever within 24h after infusion which became attenuated on day three. Concurrently with increase in serum cortisol, CRP, IL-6 and TNF-α, on day 1 and 2, total serum T3 (TT3), free T3 (fT3), total T4 (TT4) and fT4 decreased with a nadir on day 2 in association with an increase in the fT4/fT3 ratio and reverse T3 (rT3) levels. All thyroid function changes returned to the baseline levels on day 3, with cytokines still at higher levels, although lower than those on day 2. Serum TSH remained essentially unchanged throughout the study. The changes in thyroid hormones were at least in part explained by the increased TNF-α, but not by IL-6. ZA induces short term changes in thyroid hormones, characteristic of nonthyroidal illness syndrome (NTIS), in association with an increase in TNF-α and IL-6.