Reference interval for type III procollagen (PIIINP) using the Advia centaur PIIINP assay in adults and elderly

Figures & data

Figure 1. Histograms of the PIIINP measurements. Bin size 2. (A) Non-transformed frequencies. Vertical full lines indicate the calculated reference interval (4.42–16.0 µg/L), the vertical dotted lines indicated the 95% C.I. (B) Box-Cox transformed frequencies.

Figure 2. Procollagen III, N-terminal Propeptide (PIIINP) serum levels in different age groups. Box plots showing the median, the 25th and 75th quartiles, and the 2.5% and 97.5% quantiles values.

Table 1. PIIINP concentration by age group and sex.

	PIIINP μg/L
Group (n)	Mean	2.5th percentile	95% CI	97.5th percentile	95% CI	p-value
Total (386)	8.67	4.42	4.20–4.65	16.0	15.04–17.02
Male (142)	8.58	4.89	4.60–5.22	15.62	13.99–17.56	0.63
Female (244)	8.73	4.21	3.92–4.52	16.37	15.16–17.68
Age range (n)
20–29 (45)	8.73	4.21	3.49–5.05	15.41	13.29–17.81
30–39 (53)	8.24	4.1	3.58–4.71	15.89	13.25–19.20
40–49 (54)	7.87	3.84	3.22–4.53	13.63	11.98–15.45
50–59 (43)	7.76	4.93	4.60–5.31	15.98	11.56–30.69
60–69 (41)	8.65	4.83	4.24–5.52	15.24	12.80–18.30
70–89 (110)	8.88	4.73	4.38–5.14	17.02	14.88–19.62
>80 (40)	10.71	5.42	4.44–6.54	17.9	15.61–20.41

Abbreviations: n: number; PIIINP: procollagen type III N-terminal pro-peptide; CI: confidence interval. Significance set to p < 0.05.