Reference intervals for 12 clinical laboratory tests in a Danish population: The Lolland-Falster Health Study

Figures & data

Table 1. Baseline characteristics of participants in Lolland-Falster Health Study aged 18 + years: Determinants, 2016–2019.

	Males			Females			Total
	n	%	Median (IQR)	n	%	Median (IQR)	n	%	Median (IQR)
Total	5405	48.5%		5733	51.5%		11138	100%
Age (years)			59 (22)			57 (22)			58 (22)
18-29	454	8.4%		472	8.2%		926	8.3%
30-39	420	7.8%		490	8.6%		910	8.2%
40-49	743	13.7%		929	16.2%		1672	15.0%
50-59	1151	21.3%		1373	24.0%		2524	22.7%
60-69	1363	25.2%		1367	23.8%		2730	24.5%
≥70	1274	23.6%		1102	19.2%		2376	21.4%
BMI
Underweight	35	0.7%		105	1.8%		140	1.3%
Normal	1536	28.4%		2370	41.3%		3906	35.1%
Overweight	2462	45.6%		1840	32.1%		4302	38.6%
Obese	1343	24.8%		1391	24.3%		2734	24.5%
Missing	29	0.5%		27	0.5%		56	0.5%
Waist-hip ratio
≥ 0.90	4318	79.9%
≥ 0.85				2640	46.1%
Blood pressure
Normal blood pressure	725	13.4%		1679	29.3%		2404	21.6%
Prehypertension	1755	32.5%		1458	25.4%		3213	28.9%
Known hypertension	1424	26.3%		1287	22.5%		2711	24.3%
Undiagnosed hypertension	1137	21.0%		958	16.7%		2095	18.8%
Missing	364	6.7%		351	6.1%		715	6.4%
Dyslipidaemia
Total cholesterol ≥5 mmol/l	2627	48.6%		3327	58.0%		5954	53.5%
LDL-cholesterol ≥3 mmol/l	2119	39.2%		2592	45.2%		4704	42.2%
HDL-cholesterol ≤1 mmol/l	1287	23.8%		443	7.7%		1730	15.5%
Triglycerides ≥2 mmol/l	2018	37.3%		1437	25.1%		3455	31.0%
Any dyslipidaemia	3806	70.4%		3913	68.3%		7719	69.3%
Persons fulfilling inclusion criteria for being healthy
Yes	1094	20.2%		1060	18.5%		2154	19.3%
No	4311	79.8%		4673	81.5%		8984	80.7%

IQR: Interquartile range.

Table 2. Baseline characteristics of reference population.

	Males	Females	Total
Total (n(%))	1060 (49.2%)	1094 (50.8%)	2154 (100%)
Age (n(%))
18-29	220 (20.8%)	189 (17.3%)	409 (19.0%)
30-39	158 (14.9%)	150 (13.7%)	308 (14.3%)
40-49	229 (21.6%)	275 (25.1%)	504 (23.4%)
50-59	226 (21.3%)	267 (24.4%)	493 (22.9%)
60-69	149 (14.1%)	157 (14.4%)	306 (14.2%)
≥70	78 (7.3%)	56 (5.1%)	134 (6.2%)
Physical characteristics (median (IQR))
Height (cm)	180 (9.0)	167 (9.0)	173 (14.0)
Weight (kg)	80.7 (14.5)	65.5 (12.1)	72.6 (17.3)
BMI (kg/m2)	25 (3.8)	23.6 (4.2)	24.3 (4.1)
Waist-hip ratio	0.9 (0.1)	0.8 (0.1)	0.9 (0.1)

IQR: Interquartile range.

Table 3. Lower and upper limits for reference intervals in apparently healthy males and females.

		Present study		NORIP [5,6,7]
Blood component	n in present study^a	Lower 2.5th percentile and 90% CI	Upper 97.5th percentile and 90% CI	Lower 2.5th percentile with 90% CI	Upper 97.5th percentile and 90% CI
Alanine aminotransferase, U/L
Females, ≥18 years	1085	14.3 (14.0–14.6)	47.6 (43.6–51.6)	7.0 (6.0–8.0)	45.0 (37.0–50.0)
Males, ≥18 years	1053	17.1 (16.7–17.5)	74.1 (62.1–86.2)	10.0 (9.0–11.0)	68.0 (56.0–87.0)
Albumin, g/L
Females and males, 18–39 years	708	36.1 (35.5–36.7)	46.8 (46.4–47.1)	35.8 (35.2–36.3)	47.2 (46.9–48.1)
Females and males, 40–69 years	1294	35.4 (35.1–35.7)	44.5 (44.3–44.8)	35.8 (35.2–36.3)	45.4 (45.1–45.9)
Females and males, ≥70 years	132	33.5 (32.6–34.4)	42.8 (42.2–43.5)	34.5 (33.8–34.9)	45.4 (45.1–45.9)
Alkaline phosphatase, U/L
Females and males, ≥18 years	2137	41.1 (40.0–42.2)	115.3 (110.8–119.8)	44.0 (35.0–48)	95 (90.0–113)
Bilirubin, µmol/L
Females and males, ≥18 years	2143	4.0 (3.9–4.0)	22.2 (20.6–23.8)	5.1 (4.7–5.4)	26 (24.3–28.4)
Creatinine, µmol/L				^b
Females, ≥18 years	1086	49.6 (48.7–50.6)	85.4 (83.8–87.0)	45.0	90.0
Males, ≥18 years	1054	63.8 (63.0–64.4)	106.2 (104.1–108.3)	60.04	105.0
High-density lipoprotein cholesterol, mmol/L
Females, ≥18 years	1082	0.99 (0.96–1.03)	2.57 (2.48–2.66)	1.04 (0.98–1.08)	2.68 (2.59–2.79)
Males, ≥18 years	1053	0.82 (0.79–0.85)	2.17 (2.10–2.24)	0.8 (0.75–0.85)	2.14 (2.09–2.28)
Hemoglobin, mmol/L
Females, ≥18 years	1082	7.30 (7.18–7.42)	9.34 (9.26–9.41)	7.1 (7.03–7.15)	9.3 (9.21–9.45)
Males, ≥18 years	1056	8.14 (8.05–8.24)	10.27 (10.20–10.35)	8.1 (8.00–8.18)	10.30 (10.12–10.42)
Iron, µmol/L
Females and males, ≥18 years	2144	6.1 (5.7–6.5)	29.2 (28.3–30.1)	9.0 (8.3–9.4)	33.7 (33.2–35.0)
Low-density lipoprotein cholesterol, mmol/L
Females and males, 18–29 years	401	0.97 (0.81–1.12)	3.81 (3.57–4.05)	1.21 (0.58–1.36)	4.00 (3.68–4.30)
Females and males, 30–49 years	791	1.32 (1.27–1.37)	4.29 (4.18–4.41)	1.47 (1.16–1.61)	4.25 (3.95–4.95)
Males and females, ≥50 years	910	1.67 (1.54–1.8)	4.99 (4.81–5.17)	1.94 (1.73–2.05)	5.08 (4.89–5.86)
Thrombocytes, 10^9/L
Females, ≥18 years	1086	176 (172–181)	379 (372–387)	165 (159−173)	387 (375−403)
Males, ≥18 years	1054	156 (152–160)	343 (333–354)	145 (138−149)	348 (334−358)
Total cholesterol, mmol/L
Females and males, 18–29 years	406	2.70 (2.56–2.83)	6.04 (5.67–6.40)	2.95 (2.79–3.14)	5.89 (5.78–6.52)
Females and males, 30–49 years	807	3.23 (3.18–3.29)	6.69 (6.53–6.85)	3.35 (3.13–3.51)	6.75 (6.41–7.06)
Females and males, ≥50 years	924	3.81 (3.71–3.90)	7.30 (7.17–7.42)	3.89 (3.79–4.01)	7.35 (7.22–7.62)
Triglycerides, mmol/L
Females and males, ≥18 years	2148	0.51 (0.49–0.52)	3.79 (3.57–4.01)	0.45 (0.42–0.48)	2.39 (2.21–2.55)

^a Persons with missing values excluded. A few individuals had missing values in each parameter and therefore the total number of individuals per analysis is less than 2154.

^b 90% CIs for NORIP creatinine were not available.

Figure 1. Relative change and 90% confidence intervals of LOFUS reference values compared to NORIP values, lower limit. Relative change is computed as (X_LOFUS - X_NORIP)/X_NORIP, and similarly for confidence limits. Black dots denote relative changes whose confidence interval overlaps zero (dashed line).

Figure 2. Relative change and 90% confidence intervals of LOFUS reference values compared to NORIP values, upper limit. Relative change is computed as (X_LOFUS - X_NORIP)/X_NORIP, and similarly for confidence limits. Black dots denote relative changes whose confidence interval overlaps zero (dashed line).

Rustad P, Felding P, Franzson L, et al. The Nordic Reference Interval Project 2000: recommended reference intervals for 25 common biochemical properties. Scand J Clin Lab Invest. 2004;64(4):271–284.

 PubMed Web of Science ®Google Scholar

Nordin G, Mårtensson A, Swolin B, et al. A multicentre study of reference intervals for haemoglobin, basic blood cell counts and erythrocyte indices in the adult population of the Nordic countries. Scand J Clin Lab Invest. 2004;64(4):385–398.

 PubMed Web of Science ®Google Scholar

Mårtensson A, Rustad P, Lund H, et al. Creatininium reference intervals for corrected methods. Scand J Clin Lab Invest. 2004;64(4):439–441.

 PubMed Web of Science ®Google Scholar

Data availability statement

Data from the study can be made available via Region Zealand following the Danish Data Protection Regulation.