The magnesium load test: III. correlation of clinical and laboratory data in infants from one to six months of age.

A study of 64 infants from one to six months of age was made using the 32-hour parenteral magnesium load test. Most of the infants were studied for neuromuscular hyperirritability or other signs compatible with magnesium deficiency; some with unrelated problems served as controls. Magnesium retention below 40 per cent was found in 26 infants who presented with minor sign or signs that were otherwise explained, as by infection. Twelve who retained 72 per cent of the load were normal or small at birth, amply fed on demand, and grew at accelerated rates, increasing from the 50th to the 88th mean percentile by ten weeks, when they were "fat, hungry, jumpy babies," exemplifying the Mg deficiency syndrome of growth. Seven infants of 8.2 plus or minus 1 weeks had had one or more sudden, transient episodes that included: apnea, gasping, tonic or tonic-clonic fits, and flaccidity, often with pallor, cyanosis, eye signs, sweating, or tearing. Despite preload Mg in two, the group retained 88 per cent of the load. Mg appeared to be specific therapy in high retention groups. The signs are nonspecific but resemble premonitory signs and the type of episode that may occur in the sudden infant death syndrome (SIDS), suggesting a possible link between magnesium depletion and SIDS.