Table 2.

Median values, (IQR), and [n] of available measurements of biomarkers in men <56 years of age separated into three groups with lowest, low, and normal testosterone

Hormonal biomarkers	Lowest testosterone <4.5 nmol/L (<130 ng/dL) [n = 247]	Low testosterone 4.5–7 nmol/L (130–202 ng/dL) [n = 338]	Normal testosterone >= 7 nmol/L (>202 ng/dL) [n = 4148]	P-value*
25-hydroxy-vitamin D (nmol/L)	59 (37–66) [n = 23]	45 (35–72) [n = 16]	55 (38–76) [n = 264]	0.70 [n = 303]
Estradiol (pmol/L)	36 (32–43) [n = 8]	60 (53–77) [n = 13]	90 (69–110) [n = 299]	<0.001 [n = 320]
Free testosterone (pmol/L)	62 (22–90) [n = 109]	151 (130–180) [n = 186]	330 (260–430) [n = 2592]	<0.001 [n = 2887]
LH (IU/L)	1.6 (0.8–4.2) [n = 105]	2.7(1.6–5.1) [n = 147]	3.4 (2.3–5.3) [n = 1932]	<0.001 [n = 2184]
SHBG (nmol/L)	25 (17–26) [n = 135]	20 (14–26) [n = 206]	31 (22–41) [n = 2851]	<0.001 [n = 3192]
Non-hormonal biomarkers
Age (years)	49 (44–53) [n = 247]	49 (45–52) [n = 338]	48 (45–52) [n = 4148]	0.17 [n = 4733]
BAP (U/L)	85 (70–102) [n = 60]	78 (68–101) [n = 82]	74 (62–90) [n = 1248]	<0.001 [n = 1390]
BMI (kg/m2)	28 (25–30) [n = 28]	28 (25–31) [n = 25]	27 (24–29) [n = 363]	0.16 [n = 416]
CK (U/L)	47 (47–47) [n = 1]	277 (168–310) [n = 5]	124 (88–172) [n = 52]	0.04 [n = 58]
Creatinine (µmol/L)	80 (70–95) [n = 147]	86 (77–97) [n = 168]	88 (79–97) [n = 2457]	<0.001 [n = 2772]
Free PSA (µg/L)	0.28 (0.28–0.28) [n = 1]	—	0.22 (0.13–0.31) [n = 32]	0.87 [n = 33]
HBA1c (mmol/mol)	41 (67–49) [n = 52]	41 (37–47) [n = 69]	37 (34–42) [n = 690]	<0.001 [n = 811]
LDH (U/L)	214 (178–272) [n = 49]	218 (183–298) [n = 76]	198 (170–270) [n = 1186]	0.06 [n = 1311]
Myoglobin (µg/L)	—	—	50 (46–55) [n = 2]	Not applicable
PSA (µg/L)	0.41 (0.178–0.66) [n = 32]	0.62 (0.40–1.03) [n = 60]	0.70 (0.49–1.10) [n = 1119]	<0.001 [n = 1211]
Uric acid (mmol/L)	0.39 (0.39–0.48) [n = 5]	0.37 (0.35–0.38) [n = 7]	0.34 (0.28–0.39) [n = 101]	0.08 [n = 113]

*Kruskall–Wallis test