2 For drugs with very short half-life, trough sample may no longer have detectable drug. 4 Single sample post-load and 3 to 4 weeks later, or 3 to 4 weeks into therapy if a loading dose not used is recommended as therapy is begun. 7 Peak and trough recommended if seizures are difficult to control. For slow release preparations, one sample may be sufficient. 10 Values for ranges of thyroid hormones reflect an RIA assay.
Values are likely to be different for each lab.
Contact your laboratory, or if doing assays in house, establish your own normal ranges. Overlap between normal and abnormal is great, regardless of the lab, and interpretation should be based on clinical signs.