TABLE 4.

Differences in Pre- and Postshift Blood and Urine Values of Participants by Maximum Recommended Core Body Temperature

	Tc Exceeds Maximum Recommended*
	Yes (n = 17)		No (n = 41)
	Preshift Mean	Postshift Mean	Preshift Mean	Postshift Mean	P†
Blood
Sodium (corrected)‡	137.82	137.82	138.09	138.56	0.34
Potassium	4.49	4.36	4.42	4.22	0.76
Chloride	108.82	108.18	108.56	108.24	0.66
CO2	22.41	22.65	23.27	23.78	0.66
BUN	15.35	16.29	14.15	16.32	0.11
Creatinine	0.95	1.28	1.11	1.37	<0.05§
BUN/creatinine ratio	16.65	13.44	12.91	12.35	<0.01§
Glucose	112.76	106.65	107.29	107.37	0.46
Osmolality	287.39	287.39	287.19	288.91	0.23
Urine
Specific gravity	1.023	1.026	1.023‖	1.029	0.59

^*T_c greater than 101.3°F for acclimatized employees or greater than 100.4°F for unacclimatized employees.

^†Wilcoxon test; P values when comparing the difference in pre- and postshift blood and urine values between participants with maximum T_c that do and do not exceed the American Conference of Governmental Industrial Hygienists heat strain criteria.

^‡Sodium is corrected for participants with glucose concentrations greater than 200 mg/dL using the formula: corrected sodium = measured sodium + 0.016 (glucose − 100).

^§P ≤ 0.05 was considered statistically significant.

^‖n = 40.

BUN, blood urea nitrogen; T_c, core body temperature.