Endocrinology and Metabolism Section, Louisiana State University Health Sciences Center, Shreveport, Louisiana, USA.
Endocr Pract. 2012 Nov-Dec;18(6):894-7. doi: 10.4158/EP12130.OR.
To illustrate that severe primary hypothyroidism alone may not be enough to cause hyponatremia in the otherwise healthy ambulatory patient.
A retrospective chart review was conducted using an academic health center enterprise-wide electronic health record to identify 10 patients with primary hypothyroidism and same-day serum thyroid-stimulating hormone (TSH), sodium, creatinine, and calculated glomerular filtration rate (GFR). Same-day free triiodothyronine or free thyroxine was also recorded if tested. Patients were included in our case series if they met the following inclusion criteria: TSH level >100 μU/mL and same-day sodium and creatinine levels. All laboratory tests were collected on an outpatient basis.
The 10 subjects (2 men and 8 women) were ages 19 to 97 years (median, 51.5 years). Median TSH was 193 μU/mL (range, 104.2 to 515.6 μU/mL; normal, 0.40 to 5.50 μU/mL) with median sodium of 138 mmol/L (range, 136 to 142 mmol/L; normal, 135 to 146 mmol/L). The lowest sodium was 136 mmol/L with concurrent TSH of 469.7 μU/mL, free triiodothyronine of 1.0 pg/mL (normal, 1.8 to 4.6 pg/mL), and free thyroxine of 0.2 ng/dL (normal, 0.7 to 1.8 ng/dL). Median GFR was 67.5 mL/min/1.73 m2 (range, 44 to 114 mL/min/1.73 m2; normal, 90 to 120 mL/min/1.73 m2).
In our small series of patients with extreme TSH elevations, none had a serum sodium level below normal (<135 mmol/L), even in the presence of a reduced GFR. Hyponatremia can be a common occurrence in hospitalized and/or chronically ill patients; however, in an otherwise relatively healthy ambulatory patient, hypothyroidism, even when severely undertreated, may be a less clinically relevant cause of hyponatremia.
说明单纯严重原发性甲状腺功能减退症可能不足以导致门诊健康患者发生低钠血症。
通过使用学术医疗中心的企业级电子健康记录进行回顾性图表审查，确定了 10 例原发性甲状腺功能减退症和同日血清促甲状腺激素（TSH）、钠、肌酐和计算肾小球滤过率（GFR）的患者。如果进行了测试，还记录了同日游离三碘甲状腺原氨酸或游离甲状腺素。如果患者符合以下纳入标准，则将其纳入本病例系列：TSH 水平>100μU/mL 及同日钠和肌酐水平。所有实验室检查均在门诊采集。
10 名受试者（2 名男性和 8 名女性）年龄为 19 至 97 岁（中位数为 51.5 岁）。中位 TSH 为 193μU/mL（范围为 104.2 至 515.6μU/mL；正常值为 0.40 至 5.50μU/mL），中位钠为 138mmol/L（范围为 136 至 142mmol/L；正常值为 135 至 146mmol/L）。最低钠为 136mmol/L，同时 TSH 为 469.7μU/mL，游离三碘甲状腺原氨酸为 1.0pg/mL（正常值为 1.8 至 4.6pg/mL），游离甲状腺素为 0.2ng/dL（正常值为 0.7 至 1.8ng/dL）。中位 GFR 为 67.5mL/min/1.73m2（范围为 44 至 114mL/min/1.73m2；正常值为 90 至 120mL/min/1.73m2）。
在我们的 TSH 极度升高的小系列患者中，即使存在 GFR 降低，也没有患者的血清钠水平低于正常值（<135mmol/L）。低钠血症在住院和/或慢性疾病患者中很常见；然而，在其他相对健康的门诊患者中，即使甲状腺功能减退症治疗不足，也可能是低钠血症不太相关的原因。
