Approach to a low TSH level: Patience is a virtue

Abstract

Confronted with a low serum level of thyrotropin (thyroid-stimulating hormone, TSH), physicians should not jump to the conclusion that it is due to a hyperthyroid state, as other conditions and some drugs can be associated with a TSH level that is slightly low (0.1–0.4 μIU/mL) or frankly suppressed (<>

Key points

A low TSH value should always be followed up by measuring the thyroid hormones, ie, thyroxine (T₄) and triiodothyronine (T₃).

Serum levels of free thyroid hormones should be used when interpreting an abnormal TSH level, especially in the acute and inpatient settings.

A low TSH level is not always the result of suppression by elevations in circulating thyroid hormones.

A low TSH level in the setting of normal levels of free thyroid hormones should always be reassessed in 4 to 6 weeks before making a diagnosis.

Overt hyperthyroidism is usually associated with a frankly suppressed TSH (<>

• Copyright© 2010 The Cleveland Clinic Foundation

How soon after hip fracture surgery should a patient start bisphosphonates?

Patients with an osteoporotic hip fracture suffer from profound morbidity and are at a heightened risk of death. It is therefore essential that they receive treatment with a bisphosphonate known to modify the subsequent risk of fracture at any site—eg, alendronate (Fosamax), risedronate (Actonel), or zoledronic acid (Reclast).

However, there is concern that starting a bisphosphonate too soon after surgery could disrupt bone remodeling and delay fracture repair.

A meta-analysis by Bolland et al⁵ examined the effect of other osteoporosis treatments on mortality rate, using randomized controlled trials that lasted more than 12 months and that reported more than 10 deaths. The authors concluded the following:

• In the trials in which bisphosphonates reduced the mortality rate, the mortality rate in the placebo group was higher than 10 per 1,000 patient-years

• The effect of osteoporosis treatment on the mortality rate in a frail, elderly population is evident using agents with proven efficacy in reducing vertebral and nonvertebral fractures, eg, alendronate, risedronate, and zoledronic acid

How soon after hip fracture surgery should a patient start a bisphosphonate? The only data we have are from a single randomized controlled trial designed to measure fracture risk reduction in osteoporotic patients with hip fracture using intravenous zoledronic acid 5 mg compared with placebo.² A post hoc analysis of this study¹ generated the limited clinical data we have on the optimal timing of the treatment. Linking these study data with the laboratory data, one would intuit that delaying the infusion of zoledronic acid for at least 2 weeks after hip fracture repair would offer a clinical reduction in fracture risk and improvement (or stabilization) in bone mineral density by 12 months, and a reduction in the rate of all-cause mortality beginning at 16 months.

• Copyright© 2010 The Cleveland Clinic Foundation