recently reported in Clinical Chemistry reference cutoffs for 4 urinary steroid metabolites and derived ratios for differentiating 21OHD and PORD (1).
These data covered all age groups and included 21OHD and PORD (2).
 Nonstandard abbreviations: 21OHD, 21-hydroxylase deficiency; PORD, P450 oxidoreductase deficiency.
The objective of this study was to identify biochemical markers for the differential diagnosis of C21OHD, PORD, and TH17OHP and to set the cutoff in Japanese infants <6 months old, the period during which most patients with C21OHD or PORD are diagnosed (7).
We recruited 29 infants with C21OHD, 9 with PORD, and 67 with TH17OHP, and 1341 control infants from 2000 through 2009 at Keio University Hospital and 45 other hospitals throughout Japan (Table 1).
We measured Ptl and the cortisol metabolites 5[alpha]-tetrahydrocortisone and 5[beta]-tetrahydrocortisone (sum of these metabolites termed THEs) and calculated the ratio of Ptl to the cortisol metabolites (Ptl/THEs) (5,9) to differentiate C21OHD and PORD from TH17OHP and controls.
Statistical analysis of DHEA, androgen, and 11OHAD4 metabolites was carried out by Mann-Whitney U-test between C21OHD and PORD. A P value of < 0.05 was considered statistically significant.
DIFFERENTIATION OF C21OHD AND PORD FROM TH17OHP AND CONTROLS
Ptl [median (range) mg/gcreatinine] was 10 (0.079-36) in C21OHD, 1.5 (0.42-2.6) in PORD, 0.006 (<0.00-10.086) in TH17OHP, and <0.001 (<0.001-0.064) in controls.
3 shows the results of urinary metabolites of 17,20-lyase products (mg/g creatinine) in C21OHD and PORD. DHEA metabolites were 97 (11-505) in C21OHD and 4.0 (0.15-17) in PORD.
We established a 2-step biochemical differential diagnosis for C21OHD and PORD by urinary steroid profile.