School of Veterinary Sciences, University of Bristol, Bristol, UK.
Dick White Referrals, Station Farm, Newmarket, UK.
J Feline Med Surg. 2021 Oct;23(10):928-935. doi: 10.1177/1098612X20983973. Epub 2021 Jan 19.
The study aimed to document the incidence of erythrocyte microcytosis in a population of hyperthyroid cats referred for radioiodine (RAI) treatment. Microcytosis has been observed but not described in feline hyperthyroid patients and is associated with hyperthyroidism in humans.
Retrospective clinicopathological data were collected for cats undergoing RAI between January and December 2017. Microcytosis was defined as mean cell volume (MCV) <41.3 fl using the ADVIA 2120 haematology analyser (Siemens) and identified on blood smear examination by a haematology laboratory scientist or board-certified specialist in veterinary clinical pathology. Hyperthyroidism was classified as mild (total thyroxine [TT4] 60-124.9 nmol/l), moderate (TT4 125-250 nmol/l) or severe (TT4 ⩾251 nmol/l) immediately before RAI. Data were analysed descriptively and using a Pearson correlation coefficient to test the relationship between TT4 and microcytosis, and time elapsed between first diagnosis and MCV.
There were 41 female and 37 male cats with an age range of 7.2-20.8 years. Most cats were non-pedigree (98.7%). Microcytosis (median MCV 39.8 fl, interquartile range 32.3-41.2) was present in 29.5% (23/78) of the cats. Of the 23 microcytic samples, 86.9% (20/23) were confirmed as such on smear examination. Of mildly, moderately and severely hyperthyroid cats, 23% (6/26), 28.1% (9/32) and 40% (8/20) were microcytic, respectively. Two microcytic cats had low red blood cell counts (<6 × 10/l) and low haemoglobin concentration (<8.2 g/dl). There was no correlation between TT4 or time elapsed from first diagnosis and MCV. Microcytosis resolved in 77.7% (7/9) of cases with follow-up. One microcytic cat had significant comorbidities (portosystemic shunt).
Microcytosis was present in a significant proportion of hyperthyroid cats, most without clinically significant comorbidities, and resolved in some following RAI.
本研究旨在记录接受放射性碘（RAI）治疗的甲状腺功能亢进猫群中红细胞小细胞症的发生率。小细胞症已在猫甲状腺功能亢进患者中观察到，但尚未描述，并且与人类甲状腺功能亢进有关。
收集了 2017 年 1 月至 12 月间接受 RAI 的猫的回顾性临床病理数据。使用 ADVIA 2120 血液分析仪（西门子）定义小细胞症为平均细胞体积（MCV）<41.3 fl，并由血液学实验室科学家或兽医临床病理学委员会认证专家在血涂片检查中识别。甲状腺功能亢进分为轻度（总甲状腺素 [TT4] 60-124.9 nmol/L）、中度（TT4 125-250 nmol/L）或重度（TT4 ⩾251 nmol/L），在接受 RAI 治疗前即刻进行分类。使用 Pearson 相关系数对 TT4 和小细胞症之间的关系以及首次诊断和 MCV 之间的时间间隔进行描述性分析和检验。
41 只为雌性，37 只为雄性，年龄范围为 7.2-20.8 岁。大多数猫是非纯种（98.7%）。29.5%（23/78）的猫存在小细胞症（中位数 MCV 39.8 fl，四分位距 32.3-41.2）。在 23 个小细胞样本中，86.9%（20/23）在涂片检查中得到证实。轻度、中度和重度甲状腺功能亢进的猫中，分别有 23%（6/26）、28.1%（9/32）和 40%（8/20）为小细胞症。有 2 只小细胞症猫的红细胞计数<6×10/l（低）和血红蛋白浓度<8.2 g/dl（低）。TT4 或首次诊断与 MCV 之间没有相关性。在有随访的 77.7%（7/9）病例中，小细胞症得到缓解。有 1 只小细胞症猫存在严重的并存疾病（门体分流）。
甲状腺功能亢进猫群中存在显著比例的小细胞症，大多数无明显并存疾病，在接受 RAI 治疗后部分得到缓解。
