| |
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].
