Case: "Lithium and radioactive iodine" successfully treated one patient with "Metazole-induced agranulocytosis" | 2021ENDO

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Introduction: On March 20th, US time (early morning on the 21st, Beijing time), the 2021 American Society of Endocrinology Annual Meeting (ENDO) was officially held.
This conference covers many fields of endocrinology, and many research results have been published.

Dr.
Iuri Goemann from the University of Rio de Janeiro in Brazil reported a case of "Lithium and radioactive iodine successfully treated a patient with methimazole-induced agranulocytosis".
Yimaitong compiled and shared with you.

Antithyroid drugs (ATD) treatment is the first-line treatment for Graves' hyperthyroidism.

The occurrence of agranulocytosis is related to ATD treatment.
Although rare, it can be life-threatening.

 For patients who have recovered from agranulocytosis induced by ATD, surgery or radioactive iodine (RAI) treatment is the appropriate choice to restore the patient's normal thyroid state.

Here, a case of agranulocytosis related to the use of ATD is reported, using lithium therapy before RAI to control thyrotoxicosis and prevent the deterioration of hyperthyroidism.

 Case report A 74-year-old female patient with a history of hypertension has lost 12 pounds (about 5.
5 kg) in the past 2 months, accompanied by palpitations and shortness of breath.

No fever, heart rate 110 beats per minute, blood pressure 149/80mmHg, mild tremor and moderate diffuse goiter.

The patient’s visual acuity was normal, and laboratory evaluations showed TSH<0.
01 uIU/mL (0.
35-5.
5uIU/mL), FT4 3.
11 ng/dL (0.
51-1.
65ng/dL) and TRAb 40U/L (<1.
0 U/L), The results are consistent with thyrotoxicosis caused by Graves disease.  Figure 1 Case follow-up data.
The patient immediately received methimazole (MMI) 15 mg and metoprolol.

After four weeks, the symptoms disappeared and the thyroid function test (TFT) improved.

However, after two months of treatment, the patient was hospitalized with fever, diarrhea and abdominal pain.

The white blood cell count (WBC) is 650/μL, and the neutrophil count is 90/μL.

Diagnosed with gastroenteritis and agranulocytosis, stopped MMI.

 The symptoms disappeared after 7 days, the neutrophil count was 2200/ul, and the TFT level was within the acceptable range (FT4 1.
25ng/dL; TT3 1.
67ng/ml; TSH<0.
02uIU/ml).

He was discharged from the hospital without ATDs and planned to undergo 20 mCi RAI treatment.

However, due to the restrictions of the COVID-19 pandemic, RAI treatment had to be postponed.

Three weeks later, the TFT level deteriorated.
Because the patient refused thyroidectomy, he was given lithium carbonate 300 mg tid.

The use time of lithium salt ranges from 12 days before RAI treatment to 7 days after RAI treatment.

No side effects related to lithium therapy have been reported.

 Seven days after RAI treatment, the patient's TFT examination results were as follows: FT4 1.
43ng/dL, TT3 2.
05 ng/ml, TSH<0.
02 uIU/ml, 1 month later, the thyroid function was normal, without thyroid medication, and the follow-up is still underway.

 Case analysis After RAI treatment in patients with Graves disease, serum thyroid hormone (TH) levels usually increase, which is worthy of attention and concern because of the increased risk of cardiovascular complications.

 Previous studies have shown that the use of lithium before RAI treatment can prevent changes in serum TH concentration and improve the effectiveness of RAI treatment.

In the above cases, lithium therapy is used to control hyperthyroidism and prevent further increases in TH levels associated with RAI therapy.

Lithium is particularly suitable for patients who experience ATD-related side effects before receiving the final treatment (radioactive iodine or thyroidectomy).

The anti-thyroid effect of lithium in this case needs to be further studied.