Table 3.

Biochemical parameters at diagnosis and imaging characteristics of the study participants according to FHH-genotype

	FHH-negative (n = 36, 54.5%)	FHH-positive (n = 30, 45.5%)	Reference range	P
Biochemical parameters at diagnosis
Serum Ca2+ (mmol/L)	2.64 (0.24)	2.73 (0.21)	2.10–2.55	0.24
Highest serum Ca2+ (mmol/L)	2.78 (0.32)	2.86 (0.25)		0.43
Serum PTH (pmol/L)	13.18 (11.36)	6.50 (5.77)	1.60–6.90	<0.001
Serum phosphate (mmol/L)	0.84 (0.26)	0.91 (0.26)	0.87–1.45	0.20
Serum Mg2+ (mmol/L)*	0.81 (0.09)	0.93 (0.18)	0.66–1.07	<0.001
eGFR (mL/min/1.73m2)	70.76 ± 3.81	84.42 ± 3.92		0.04
25-hydroxivitamin D (nmol/L)	51.02 (50.36)	49.00 (36.9)	>50	0.53
CCCR ratio	0.009 ± 0.001	0.009 ± 0.001		0.68
Imaging characteristics
99 m Tc-sestamibi parathyroid scintigraphy (done), n (%)	34 (94%)	21 (70%)		0.02
Findings
Normal, n (%)	20 (59%)	19 (90%)		0.03
Uniglandular involvement, n (%)	12 (35%)	2 (10%)
Multiglandular involvement, n (%)	2 (6%)	0 (0%)
Neck ultrasound (done), n (%)	25 (69%)	21 (70%)		0.96
Findings
Normal, n (%)	13 (52%)	19 (90%)		0.01
Uniglandular involvement, n (%)	12 (48%)	2 (10%)
Neck CT scan (done), n (%)	12 (33%)	9 (30%)		0.79
Findings
Normal, n (%)	10 (83%)	7 (78%)		0.75
Uniglandular involvement, n (%)	2 (17%)	1 (11%)
Multiglandular, n (%)	0 (0%)	1 (11%)
18F-Choline PET/CT (done), n (%)**	6 (17%)	0 (0%)		0.03
Findings
Negative result, n (%)	0 (0%)	-
Uniglandular involvement, n (%)	5 (83%)	-
Multiglandular involvement, n (%)	1 (17%)	-

Data are reported as mean ± standard error of the mean (Gaussian distribution) and as median (p25-p75) (non-Gaussian distribution)

FHH familial hypocalciuric hypercalcemia, Ca²⁺, albumin-adjusted calcium, PTH parathormone, Mg²⁺ magnesium, eGFR estimated glomerular filtration rate, CCCR calcium creatinine clearance ratio, CT computed tomography, PET/CT positron emission tomography/computed tomography

*Available in 49 participants (29 FHH-negative and 20 FHH-positive) ^**Only available in two centres after 2016