Seasonal incidence of subclinical vitamin K deficiency during early newborn period.

Eleven-Sixty six healthy, non-vitamin K treated and exclusively breast-fed 5-day-old newborns were screened with PIVKA-II and Hepaplastin test for subclinical vitamin K deficiency for two years. PIVKA-II values in 96 babies (8.2%) ranged from 1 to 8 micrograms/ml. These babies were divided into two groups: 83 (86.5%) had relatively low values ranging from 1 to 2 micrograms/ml, and 13 (13.5%) had higher values ranging from 2 to 8 micrograms/ml. Eleven babies in the latter group (84.6%) had a seasonal deviation in incidence in the summer and early fall (p less than 0.05). This seasonal variation in severe subclinical vitamin K deficiency during the early newborn period corresponds with the results of an epidemical survey of idiopathic late onset hemorrhagic disease in newborns in Japan, suggesting similar causative factors in both of these hemorrhagic diseases.