Table 2. Biochemical parameters across the three study periods.

All data are presented as median (IQR). Differences between groups were evaluated using the Kruskal-Wallis test followed by Bonferroni-adjusted post hoc tests. Asterisks indicate statistical significance: *p<0.05; **p<0.01.

Ca: calcium, P: phosphate, Mg: magnesium, iPTH: intact parathyroid hormone, ALP: alkaline phosphatase, IQR: interquartile range, ND: not determined in post hoc tests

Parameter	Pre-COVID-19 period (pre)	COVID-19 pandemic period (pandemic)	Post-COVID-19 period (post)	p-value	Post hoc test
					(Bonferroni)	p-value
Ca (mg/dL)	9.6 (9.1-10.1)	9.6 (9.1-10.0)	9.5 (9.0-10.0)	0.204	ND
P (mg/dL)	5.4 (4.8-5.9)	5.6 (5.0-6.1)	5.7 (5.2-6.4)	<0.01**	Pre vs. pandemic	0.034*
					Pandemic vs. post	0.043*
					Pre vs. post	<0.01**
iPTH (pg/mL)	16 (9-32.5)	12 (8-28.5)	15 (8-27.0)	0.071	ND
ALP (U/L)	212.0 (181.0-260.0)	212.0 (176.5-257.8)	210.5 (174.0-261.0)	0.72	ND
Mg (mg/dL)	2.05 (1.9-2.3)	2.00 (1.9-2.2)	1.90 (1.8-2.2)	<0.01**	Pre vs. pandemic	0.12
					Pandemic vs. post	0.048*
					Pre vs. post	<0.01**