Pellagrous encephalopathy presenting as alcohol withdrawal delirium: A case series and literature review

Table 3 Serologic and urinary assays of niacin and its metabolites

	Deficient	Low	Adequate	High
Serum*
niacin (mg/mL)		<0.5	0.5 − 8.45	>8.45
Urine ^†
adults (men; and nongravid and 1st trimester women)	<0.5	0.5 − 1.59	1.6 − 4.29	≥4.3
2nd trimester women	<0.6	0.6 − 1.99	2 − 4.99	≥5
3rd trimester women	<0.8	0.8 − 2.49	2.5 − 6.49	≥6.5
2-pyridone/N¹-methylnicotinamide	<0.5	0.5 − 0.99	1 − 4	>4

*Niacin assays require plasma obtained using a lavender-topped tube with ethylenediaminetetraacetic acid (EDTA). Despite niacin's stability when exposed to light, heat, and humidity [36], laboratories often require that samples be wrapped in foil to protect them from light and freezing immediately [37].
†Urinary assays more accurately assess niacin intake than confirm the presence of niacin deficiency. As such, serum niacin would be appropriate test for laboratory confirmation of niacin deficiency [35].

ISSN: 1940-0640