1 Department of Paediatrics, University Hospital Motol, Charles University Prague, 2nd Faculty of Medicine, Prague, Czech Republic.
2 Department of Medical Chemistry and Clinical Biochemistry, University Hospital Motol, Charles University Prague, 2nd Faculty of Medicine, Prague, Czech Republic.
Ann Clin Biochem. 2019 Jan;56(1):90-94. doi: 10.1177/0004563218785190. Epub 2018 Jul 2.
Hypomagnesaemia is present in 40-50% of children with autosomal dominant renal cysts and diabetes syndrome (RCAD). On the contrary, the prevalence of hypomagnesaemia in children with autosomal dominant polycystic kidney disease (ADPKD) has never been examined. We aimed to investigate whether hypomagnesaemia is present in children with polycystic kidney diseases.
Children with cystic kidney diseases were investigated in a cross-sectional study. Serum concentrations of magnesium (S-Mg) and fractional excretion of magnesium (FE-Mg) were tested. Fifty-four children with ADPKD ( n = 26), autosomal recessive polycystic kidney disease (ARPKD) ( n = 16) and RCAD ( n = 12) with median age of 11.2 (0.6-18.6) years were investigated.
Hypomagnesaemia (S-Mg < 0.7 mmol/L) was detected in none of the children with ADPKD/ARPKD and in eight children (67%) with RCAD. Median S-Mg in children with ADPKD/ARPKD was significantly higher than in children with RCAD (0.89 vs. 0.65 mmol/L, P < 0.01). The FE-Mg was increased in 23% of patients with ADPKD/ARPKD (all had chronic kidney disease stages 2-4) and in 63% of patients with RCAD, where it significantly correlated with estimated glomerular filtration rate (r = -0.87, P < 0.01).
Hypomagnesaemia is absent in children with ADPKD or ARPKD and could serve as a marker for differential diagnostics between ADPKD, ARPKD and RCAD in children with cystic kidney diseases of unknown origin where molecular genetic testing is lacking. However, while hypomagnesaemia, in the absence of diuretics, appears to rule out ADPKD and ARPKD, normomagnesaemia does not rule out RCAD at least in those aged <3 years.
常染色体显性遗传性肾囊肿和糖尿病综合征（RCAD）患儿中有 40-50%存在低镁血症。相反，常染色体显性遗传性多囊肾病（ADPKD）患儿中低镁血症的患病率从未被检查过。我们旨在研究多囊肾病患儿是否存在低镁血症。
在一项横断面研究中，对囊性肾病患儿进行了调查。检测了血清镁浓度（S-Mg）和镁的分数排泄（FE-Mg）。研究了 54 名囊性肾病患儿，其中 ADPKD（n=26）、常染色体隐性多囊肾病（ARPKD）（n=16）和 RCAD（n=12），中位年龄为 11.2（0.6-18.6）岁。
ADPKD/ARPKD 患儿中无一例存在低镁血症（S-Mg<0.7mmol/L），而 RCAD 患儿中有 8 例（67%）存在低镁血症。ADPKD/ARPKD 患儿的 S-Mg 中位数明显高于 RCAD 患儿（0.89 与 0.65mmol/L，P<0.01）。23%的 ADPKD/ARPKD 患儿（所有患儿均处于慢性肾脏病 2-4 期）和 63%的 RCAD 患儿的 FE-Mg 升高，且与估计肾小球滤过率显著相关（r=-0.87，P<0.01）。
ADPKD 或 ARPKD 患儿中不存在低镁血症，在缺乏分子遗传学检测的情况下，当病因不明的囊性肾病患儿需要进行鉴别诊断时，低镁血症可作为一种标志物，有助于区分 ADPKD、ARPKD 和 RCAD。然而，在没有利尿剂的情况下，低镁血症似乎可以排除 ADPKD 和 ARPKD，但在年龄<3 岁的患者中，镁正常并不能排除 RCAD。
