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Table 1 Demographic and clinical details of patients with non-potential BH4 responsiveness and False/True-positives

From: Tetrahydrobiopterin responsiveness in phenylketonuria: prediction with the 48-hour loading test and genotype

BH4 loading test: Non-potential BH4-responsive (n = 97) Potential responder (n = 80)
BH4 extension phase:   False-positive (n = 9) True-positive (n = 58) Other1(n = 13)
Sex     
  Male 47 (48.5) 6 (66.7) 24 (41.4) 7 (53.8)
  Female 50 (51.5) 3 (33.3) 34 (58.6) 6 (46.2)
Age (years) A* 14.7 (10.3 – 23.0) 8.0 (6.4 – 11.9) 12.3 (7.7 – 17.9) 14.1 (10.4 – 19.4)
  <12 years A** 30 (30.9) 7 (77.8) 25 (43.1) 4 (30.8)
  ≥12 years 67 (69.1) 2 (22.2) 33 (56.9) 9 (69.2)
Baseline Phe (μmol/L)2 B*** C* 663 (530 – 915) 620 (528 – 831) 465 (358 – 555) 485 (386 – 590)
Mean Phe3,4 B*** C** 494 (364 – 700) 455 (406 – 553) 304 (244 – 401) 267 (239 – 407)
  <12 years B* C** 397 (290 – 441) 455 (372 – 539) 282 (227 – 400) 274 (207 – 318)
  ≥12 years4 B*** 564 (427 – 773) 440, 759 (n = 2) 332 (255 – 414) 264 (239 – 456)
Phe at diagnosis5 B***, C***     
  <600 μmol/L 3 (3.5) 0 (0.0) 26 (44.8) 4 (30.8)
  600–1199 μmol/L 13 (15.3) 2 (22.2) 26 (44.8) 3 (23.1)
  >1200 μmol/L 69 (81.2) 7 (77.8) 6 (10.3) 6 (46.2)
  1. Data are n (%) or median (interquartile range). 1 no BH4 extension phase. 2 Phe concentration at T = 0 (with Phe loading when necessary). 3 Mean Phe concentration prior to the BH4 loading test. 4 Missing in n = 14 (<30%), n = 10 (True-positives) and n = 1 (Other). 5 First Phe concentration in hospital, missing in n = 12 (<30%). A) comparing non-potential BH4-responsive and false-positive, B) comparing non-potential BH4-responsive and true-positive, C) comparing false-positive and true-positive. *P = <0.05, **P = <0.01, ***P = <0.001.