High-dose intravenous methylprednisolone is effective in subacute thyroiditis unresponsive to oral steroids

Subacute thyroiditis (SAT) relapsing or refractory to standard of care oral prednisone (OP) therapy is rare, but affected patients experience significant discomfort due to prolonged and uncontrolled neck pain. Here, we report the efficacy of high-dose intravenous methylprednisolone (IVMP) therapy in the treatment of such cases.

In this pilot study, we included 14 patients diagnosed with SAT in the period 2014-2024, in a single center. Therapy consisted of 500 mg of IVMP, divided into two weekly infusions and titrated down based on clinical response. Thyroid function tests, thyroid ultrasound, and inflammatory markers were assessed at baseline and throughout the follow-up up to 3-6 months after IVMP discontinuation.

At baseline, 4 and 10 patients had thyrotoxicosis or were euthyroid, respectively. The median (IQR) duration of treatment was 26 days (21-38). At the end of the treatment, we observed a complete clinical, ultrasonographic, and biochemical response in twelve patients (86%), whereas thirteen (93%) had immediate resolution of neck pain and thyrotoxicosis. Only one patient did not improve at the end of IVMP protocol, and she was the only one experiencing a delayed remission with persistent hypothyroidism. Mild grade 1 and 2 adverse events (hyperglycemia, arterial hypertension, and neutrophilia) occurred in 8 out of 14 patients.

IVMP therapy resulted in a rapid clinical and ultrasonographic improvement in most patients with relapsing SAT unresponsive to oral steroids. This response allowed for a shorter treatment duration, with good tolerability, minimal adverse events, and a low incidence of hypothyroidism during follow-up.