چكيده لاتين :
granulocytosis is an uncommon but A most serious adverse side effect of
thiouracil. It has been reported to affect
0.3% - 0.6% of patients treated with
thiourea-derivates. Both methimazole
(MMI) and propylthiuracil (PTU) can cause
agranulocytosis. Some data indicate that low
doses of MMI are associated with lower prevalence
of agranulocytosis than either high-dose
MMI or conventional doses of PTU. The aim of
the present study was to determine the frequency
of thionamide-associatied agranulocytosis
and to clarify the role of clinical factors such
as gender and age of patient, duration of antithyroid
therapy, dosage and type of thionamide
used, in the development of agranulocytosis.
Materials and Methods: The medical records of
all patients with hyperthyroid disease, treated
with either MMI or PTU in endocrine clinics,
were reviewed retrospectively with regard to
agranulocytosis, patient age and sex, duration of
antithyroid therapy, diagnosis, dosage, and type
of thionamide used. Between April 1985 and
September 2004, a total of 21,800 patients with
hyperthyroidism due to Gravesdisease or toxic
multinodular goiter received long term treatment
(mean duration of treatment of 15.7±8.4
months) with either MMI or PTU at endocrine
clinics of Tabriz University of Medical Sciences.
Of these, 20,840 (95.6%) patients were treated
with MMI and the remainder 960 (4.4%) received
PTU. Results: Classic agranulocytosis, defined as severe
neutropenia, accompanied by serious symptoms
and signs of infection developed in seven
cases, 5 in MMI group and 2 in PTU treated patients.
Thus the overall prevalence of thiomamide-
associated agranulocytosis in this study is
about 0.03 percent. There was no significant difference
between mean ages of patients with and
without agranulocytosis (42.2±14.8 vs 45.4±13.7
years). In the majority of cases, agranulocytosis
occurred during the first 2 months of treatment.
There was no case with agranulocytosis among
15,412 individuals treated with low doses of
MMI « 20 mg/day).
Conclusion: In conclusion the majority of cases
of agranulocytosis occurred within the first few
weeks of initiation of antithyroid therapy. This
side effect may occur at any times, regardless of
patient age, gender or duration of treatment. It
seems that the likelihood of agranulocytosis is
diminished at low doses of MMI.
