Professorial Medical Unit Teaching Hospital Anuradhapura, Anuradhapura, Sri Lanka.
Medical unit A Teaching Hospital Anuradhapura, Anuradhapura, Sri Lanka.
BMC Nephrol. 2020 Aug 5;21(1):327. doi: 10.1186/s12882-020-01959-7.
Familial distal renal tubular acidosis (dRTA) associated with mutations of solute carrier family 4 membrane - 1 (SLC4A1) gene could co-exist with red cell membrane abnormality, Southeast Asian ovalocytosis (SAO). Although this association is well described in Southeast Asian countries, it is less frequently found in Sri Lanka.
We describe six patients who had dRTA co-existing with SAO. All of them initially presented with severe hypokalemia and paralysis. They presented within a period of six months to the Teaching Hospital Anuradhapura, Sri Lanka. All had metabolic acidosis indicated by low serum bicarbonate. Three of them were having underlying chronic kidney disease as well. Those three patients had mixed high and normal anion gap metabolic acidosis indicated by low delta ratio. In all dRTA was confirmed by presence of normal anion gap, hyperchloraemia, high urine pH and positive urine anion gap. Examination of blood films of all of them revealed presence of stomatocytes and macro-ovalocytosis compatible with SAO. In relation to complications of dRTA, two patients had medullary nephrocalcinosis. Three patients had biochemical evidence of osteomalacia, with two of them having radiological evidence of diffuse osteosclerosis. One patient had secondary hyperparathyroidism and a pathological fracture.
Erythrocyte in SAO is exceptionally rigid and this abnormality is said to be evolved as it protects against Plasmodium vivax malaria and cerebral malaria cause by Plasmodium falciparum. Although two families of SAO was described earlier, SAO and dRTA combination was reported only once in a patient from Anuradhapura district. Distal renal tubular acidosis, SAO combination and its related complications including nephrocalcinosis, chronic kidney disease and metabolic bone disease was not described in Sri-Lankan literature. This case series emphasize the importance of investigating recurrent/ chronic hypokalemia to diagnose dRTA and its associations, as early correction of acidosis could prevent development of chronic kidney disease and metabolic bone disease.
家族性远端肾小管酸中毒（dRTA）与溶质载体家族 4 膜蛋白-1（SLC4A1）基因突变有关，可与红细胞膜异常、东南亚卵形细胞增多症（SAO）共存。尽管这种关联在东南亚国家已有详细描述，但在斯里兰卡却较少见。
我们描述了 6 例 dRTA 合并 SAO 的患者。他们最初均表现为严重低钾血症和瘫痪。他们在六个月内就诊于斯里兰卡安努拉达普拉教学医院。所有患者均存在代谢性酸中毒，表现为血清碳酸氢盐水平降低。其中 3 例还患有基础慢性肾脏病。这 3 例患者存在混合性高阴离子间隙和正常阴离子间隙代谢性酸中毒，表现为低 delta 比。所有 dRTA 均通过正常阴离子间隙、高氯血症、高尿 pH 值和阳性尿阴离子间隙来证实。对所有患者的血涂片检查均发现存在口形红细胞和巨卵形细胞，符合 SAO。与 dRTA 的并发症有关，2 例患者存在肾髓质钙沉着症。3 例患者存在骨软化症的生化证据，其中 2 例存在弥漫性骨质硬化的放射学证据。1 例患者存在继发性甲状旁腺功能亢进和病理性骨折。
SAO 中的红细胞异常僵硬，这种异常被认为是一种进化，因为它可以预防间日疟原虫疟疾和恶性疟原虫引起的脑型疟疾。虽然之前已经描述了 SAO 的两个家族，但 SAO 和 dRTA 组合仅在安努拉达普拉区的 1 例患者中报道过。在斯里兰卡文献中没有描述远端肾小管酸中毒、SAO 组合及其相关并发症，包括肾钙质沉着症、慢性肾脏病和代谢性骨病。本病例系列强调了对复发性/慢性低钾血症进行调查以诊断 dRTA 及其相关疾病的重要性，因为早期纠正酸中毒可预防慢性肾脏病和代谢性骨病的发生。
