Cole D E, Kooh S W, Vieth R
Department of Laboratory Medicine and Pathobiology, Banting Institute, Toronto, Ontario, Canada.
Eur J Pediatr. 2000 Jan-Feb;159(1-2):38-43. doi: 10.1007/s004310050007.
Primary infantile hypomagnesaemia is an infrequent cause of neonatal hypocalcaemic seizures but one that responds well to magnesium supplementation. We describe a 22-year-old male, first reported at 4 months of age, who is currently free of neurological deficit but has suffered from intermittent hypomagnesaemic tetany and chronic diarrhoea due to large oral magnesium supplements. Hypothesizing that modest hypercalcaemia might prevent the tetany, we conducted a trial of 5 microg/day 1,25(OH)2D3 over 5 days. Despite the resultant increase in calcium, he developed tetany with the reduction of magnesium intake and decline of serum magnesium from 0.63 to 0.39 mmol/l (normal >0.65 mmol/l). After 1,25(OH)2D3 was stopped and the parenteral magnesium injections suspended, 33% of his usual oral supplement was given instead by continuous nasogastric infusion and serum magnesium rose to 0.60 mmol/l. This regimen was better tolerated because of decreased gastrointestinal side-effects and freedom from parenteral injections. We observed that 1,25(OH)2D3 supplements do not promote magnesium retention nor does the resultant hypercalcaemia prevent hypomagnesaemic tetany.
Continuous nocturnal nasogastric infusion may be considered in lieu of parenteral therapy in primary infantile hypomagnesaemia.
原发性婴儿低镁血症是新生儿低钙惊厥的罕见病因，但对补充镁反应良好。我们描述了一名22岁男性，4个月大时首次被报道，目前无神经功能缺损，但因大量口服镁补充剂而患有间歇性低镁血症手足搐搦和慢性腹泻。假设适度高钙血症可能预防手足搐搦，我们进行了一项为期5天、每天5微克1,25(OH)2D3的试验。尽管钙水平因此升高，但随着镁摄入量减少以及血清镁从0.63毫摩尔/升降至0.39毫摩尔/升（正常>0.65毫摩尔/升），他出现了手足搐搦。在停用1,25(OH)2D3并暂停静脉注射镁后，改为通过持续鼻胃输注给予其通常口服补充量的33%，血清镁升至0.60毫摩尔/升。由于胃肠道副作用减少且无需静脉注射，该方案耐受性更好。我们观察到，补充1,25(OH)2D3既不能促进镁潴留，由此产生的高钙血症也不能预防低镁血症手足搐搦。
对于原发性婴儿低镁血症，可考虑采用持续夜间鼻胃输注代替静脉治疗。
