Serum ceruloplasmin in healthy children
Serum ceruloplasmin were measured in 372 healthy children from the age of newborn to 15 years. Of these participants, 218 (58.6%) were boys, with a mean age of 6.8 ± 4.2 years and 154 (41.4%) were girls, with a mean age of 6.2 ± 3.8 years. The mean level of serum ceruloplasmin in these healthy controls was 30.7 ± 7.8 mg/dL. Among them, 30 (8.1%) had serum ceruloplamin < 20 mg/dL, whereas 13 (3.5%) had serum ceruloplasmin < 15 mg/dL.
Age specific reference value of serum ceruloplasmin was analyzed (Table 1 & Fig. 1). These healthy children were partitioned into 16 age subgroups. Serum ceruloplasmin was at the lowest level (25.5 ± 10.1 mg/dL) in children younger than 6 months, then rapidly increased to 33.0 ± 9.3 mg/dL by the age of 1 year, and maintained 29–34 mg/dL from 1 to 15 years old. There was no age specific difference of serum ceruloplasmin in healthy children.
Table 1
Serum ceruloplasmin in healthy children stratified by age
Age group
|
No. of children
|
Ceruloplasmin concentration(mg/dL)
|
Mean
|
0-
|
5-
|
10-
|
15-
|
≥ 20
|
༜6 mths
|
20
|
25.5 ± 10.1
|
0
|
1
|
3
|
2
|
14
|
6 mths-
|
20
|
33.0 ± 9.3
|
0
|
0
|
1
|
2
|
17
|
1 year-
|
28
|
31.5 ± 8.0
|
0
|
0
|
0
|
3
|
25
|
2 yrs-
|
22
|
30.0 ± 8.3
|
0
|
1
|
1
|
0
|
20
|
3 yrs-
|
24
|
32.0 ± 6.4
|
0
|
0
|
0
|
1
|
23
|
4 yrs-
|
25
|
33.7 ± 6.5
|
0
|
0
|
0
|
0
|
25
|
5 yrs-
|
35
|
31.7 ± 5.7
|
0
|
0
|
0
|
1
|
34
|
6 yrs-
|
26
|
33.7 ± 5.0
|
0
|
0
|
0
|
0
|
26
|
7 yrs-
|
25
|
31.6 ± 5.3
|
0
|
0
|
0
|
0
|
25
|
8 yrs-
|
27
|
30.9 ± 5.9
|
0
|
0
|
0
|
1
|
26
|
9 yrs-
|
22
|
28.9 ± 6.3
|
0
|
0
|
0
|
2
|
20
|
10 yrs-
|
21
|
29.1 ± 9.8
|
0
|
0
|
3
|
2
|
16
|
11 yrs-
|
23
|
27.5 ± 7.7
|
0
|
1
|
1
|
0
|
21
|
12 yrs-
|
25
|
32.4 ± 8.8
|
0
|
0
|
0
|
0
|
25
|
13 yrs-
|
16
|
26.3 ± 6.2
|
0
|
0
|
0
|
1
|
15
|
14 yrs-
|
13
|
29.1 ± 9.7
|
0
|
0
|
1
|
2
|
10
|
Total
|
372
|
30.7 ± 7.8
|
0
|
3
|
10
|
17
|
342
|
Gender specific reference value of serum ceruloplasmin was also analyzed in these children (Table 1 & Fig. 1). The mean levels of serum ceruloplasmin in healthy boys and girls were 31.8 ± 7.7 mg/dL and 29.2 ± 7.6 mg/dL respectively, exhibiting statistically significant gender difference (p < 0.01). While analyzing gender difference in each age subgroup, serum ceruloplasmin also exhibited higher level in boys than girls, but there was no significance with the exception of 8- year subgroup.
Serum Ceruloplasmin In Children With Wilson’s Disease
As shown in Table 2, a total of 317 children were diagnosed as WD in GWCMC in last 11 years, 200 (63.1%) boys and 117 (36.9%) girls. The ratio of male:female in WD patients was 1.7:1. At diagnosis, the mean age of these patients was 6.1 ± 2.8 years (ranging, 0.6–15.0 years). The mean level of serum ceruloplasmin of them was 5.7 ± 4.7 mg/dL, which was significantly lower than that in healthy control subjects (p < 0.001). However, 6 (1.9%) of 317 WD children had normal value of serum ceruloplasmin > 20mg/dL, and they were all asymptomatic (6/261, 2.3%).
Table 2
Serum ceruloplasmin in 317 WD children stratified by age
Age group
|
No. of patients
|
Ceruloplasmin (mg/dL)
|
Mean
|
0-
|
5-
|
10-
|
15-
|
≥ 20
|
༜1 yr
|
1
|
4.0
|
1
|
0
|
0
|
0
|
0
|
1 year-
|
4
|
3.3 ± 2.2
|
3
|
1
|
0
|
0
|
0
|
2 yrs-
|
19
|
4.6 ± 3.3
|
13
|
5
|
0
|
1
|
0
|
3 yrs-
|
51
|
5.2 ± 5.1
|
33
|
12
|
3
|
0
|
3
|
4 yrs-
|
59
|
5.6 ± 4.4
|
35
|
15
|
5
|
3
|
1
|
5 yrs-
|
48
|
6.5 ± 5.6
|
25
|
12
|
8
|
1
|
2
|
6 yrs-
|
38
|
6.3 ± 5.1
|
20
|
10
|
5
|
3
|
0
|
7 yrs-
|
25
|
5.3 ± 3.7
|
16
|
4
|
5
|
0
|
0
|
8 yrs-
|
20
|
6.2 ± 4.8
|
10
|
6
|
2
|
2
|
0
|
9 yrs-
|
8
|
7.6 ± 5.2
|
3
|
3
|
1
|
1
|
0
|
10 yrs-
|
17
|
6.5 ± 4.5
|
9
|
4
|
2
|
2
|
0
|
11 yrs-
|
9
|
6.3 ± 3.2
|
4
|
3
|
2
|
0
|
0
|
12 yrs-
|
13
|
4.9 ± 3.2
|
9
|
2
|
2
|
0
|
0
|
13 yrs-
|
3
|
6.4 ± 4.3
|
1
|
1
|
1
|
0
|
0
|
14 yrs-
|
2
|
3.0 ± 1.0
|
2
|
0
|
0
|
0
|
0
|
Total
|
317
|
5.7 ± 4.7
|
184
|
78
|
36
|
13
|
6
|
Table 3. Serum ceruloplasmin in WD children with different manifestations at diagnosis.
WD patients
|
No. of patients
|
Age
(years)
|
Ceruloplasmin (mg/dL)
|
Mean
|
0-
|
5-
|
10-
|
15-
|
≥20
|
Asymptomatic WD
|
261
|
5.4±2.3a
|
5.5±4.6b
|
157
|
67
|
22
|
9
|
6
|
Symptomatic WD
|
56
|
9.4±2.6
|
7.0±4.8
|
27
|
11
|
14
|
4
|
0
|
WD w/o acute liver failure
|
302
|
6.0±2.8c
|
5.6±4.6d
|
180
|
75
|
30
|
11
|
6
|
WD w/ acute liver failure
|
15
|
9.0±2.2
|
9.3±4.7
|
4
|
3
|
6
|
2
|
0
|
Total
|
317
|
5.7±4.7
|
5.7±4.7
|
184
|
78
|
36
|
13
|
6
|
WD, Wilson’s disease. a represents comparison of age in asymptomatic WD with symptomatic WD children, p value <0.001; b represents comparison of serum ceruloplasmin in asymptomatic WD with symptomatic WD children, p value <0.05; c represents comparison of age between WD children with and without acute liver failure, p value <0.001; d represents comparison of serum ceruloplasmin between WD children with and without acute liver failure, p value <0.01.
Age specific difference of serum ceruloplasmin in WD patients was analyzed (Table 2 & Fig. 1). The youngest WD patient was a 7-month-old girl diagnosed through family screening. She was asymptomatic with low serum ceruloplasmin of 4 mg/dL but normal liver function. Among 317 WD patients, the mean level of serum ceruloplasmin varied in different age subgroups. No age specific difference of serum ceruloplasmin was shown.
Gender specific difference of serum ceruloplasmin in WD patients was also analyzed. Of the 317 WD patients, the mean age of boys was 6.2 ± 2.8 years, and that of girls was 5.9 ± 2.9 years. There was no significant gender difference of serum ceruloplasmin among 317 WD patients and inside each age subgroup (Fig. 1). However, among 261 (82.3%) asymptomatic WD patients, serum ceruloplasmin in 164 boys (6.0 ± 5.1 mg/dL) was significantly higher than that in 97 girls (4.6 ± 3.7 mg/dL) (p < 0.05), exhibiting similar trend with that in healthy children.
The association between clinical manifestation and the level of serum ceruloplasmin in WD patients was analyzed (Table 3). Of 261 asymptomatic WD children, serum ceruloplasmin was significantly lower and the age at diagnosis was much younger while compared with 56 WD children with various clinical symptoms and signs (p < 0.05, p < 0.001). Of 15 WD children with acute liver failure, serum ceruloplasmin was significantly higher and the age at diagnosis was much older while compared with 302 WD children without acute liver failure (p < 0.01, p < 0.001). None of WD patients with acute liver failure had serum ceruloplasmin > 20 mg/dL.
Serum Ceruloplasmin In Patients With Non-wd Diseases
Serum ceruloplasmin was measured in 154 patients with non-WD diseases, including acute liver failure, viral hepatitis and nephrotic syndrome. The mean age of these non-WD patients was 4.9 ± 3.7years (ranging from 1 month – 15.3years) (Table 4). All non-WD patients had serum ceruloplasmin > 20 mg/dL, with the mean level of serum ceruloplasmin (28.6 ± 11.8 mg/dL) much higher than that in WD patients (p < 0.001), but lower than healthy controls (p < 0.001).
Table 4
Serum ceruloplasmin in non-WD children.
Group
|
No. of patients
|
Ceruloplasmin (mg/dL)
|
Mean
|
0-
|
5-
|
10-
|
15-
|
≥ 20
|
Acute liver failure
|
20
|
27.4 ± 12.7
|
0
|
0
|
3
|
3
|
14
|
Viral hepatitis
|
38
|
32.5 ± 7.9
|
0
|
0
|
1
|
2
|
35
|
Nephrotic syndrome
|
96
|
26.1 ± 9.0
|
0
|
0
|
7
|
13
|
76
|
Total
|
154
|
27.8 ± 9.7
|
0
|
0
|
11
|
18
|
125
|
Serum ceruloplasmin in WD patients with R778L in the ATP7B gene
Of the 317 WD patients, 313 had genetic testing for pathogenic mutations in the ATP7B gene, with 307 bi-allelic mutations and 6 one allelic mutation. Through family screening, 21 heterozygotes and 12 wild type siblings were identified. All wild type siblings were healthy and included in healthy controls. All heterozygotes were healthy without liver dysfunction. The mean level of serum ceruloplasmin in heterozygotes was (25.6 ± 5.9mg/dL), significantly lower than healthy controls (30.7 ± 7.8mg/dL, p < 0.05), but much higher than WD patients (5.7 ± 4.7mg/dL, p < 0.001) (Fig. 1).
Among 313 WD patients, the most frequent mutation in the ATP7B gene was R778L, identified in 33.9% (106 patients) of 313 WD patients (Table 5). Of the 313 WD patients, 9 carried bi-allelic R778L mutations (R778L homozygotes), 97 had one allelic mutation of R778L together with one allelic mutation other than R778L (R778L heterozygotes) and 207 had none of R778L (No R778L). The patients with R778L homozygotes had the lowest level of serum ceruloplasmin (2.3 ± 0.5mg/dL) and significantly lower than WD children without R778L (6.2 ± 4.8 mg/dL) (p < 0.05).
Table 5
Serum ceruloplasmin in WD children carrying R778L mutation
Genotype
|
No. of patients
|
Age (yrs)
|
Ceruloplasmin (mg/dL)
|
Mean
|
0-
|
5-
|
10-
|
15-
|
≥ 20
|
R778L homozygotes
|
9
|
5.7 ± 3.1
|
2.3 ± 0.5
|
9
|
0
|
0
|
0
|
0
|
R778L heterozygotes
|
97
|
6.2 ± 3.0
|
5.2 ± 4.5
|
64
|
21
|
6
|
3
|
3
|
No R778L
|
207
|
6.1 ± 2.8
|
6.1 ± 4.8
|
108
|
57
|
29
|
10
|
3
|
Total
|
313
|
6.1 ± 2.9
|
5.7 ± 4.7
|
181
|
78
|
35
|
13
|
6
|
Diagnostic Accuracy Of Serum Ceruloplasmin In Wilson’s Disease
The ROC curves were constructed by using the data of 317 WD patients, 21 heterozygotes, 372 healthy controls and 154 non-WD patients. As shown in Fig. 2A, the conventional cutoff value of 20mg/dL gave a sensitivity of 98.1% and a specificity of 86.5%, with 63 false positives and 6 false negative. The positive and negative predictive values were 80.8% and 98.7%, respectively. The ROC curve analysis indicated that the cutoff value of serum ceruloplasmin 16.85 mg/dL provided the highest AUC value of 0.990 (95% confidence interval (CI), 0.985–0.995), with a sensitivity of 95.9% and specificity of 93.6%. The positive and negative predictive values of serum ceruloplasmin 16.85 mg/dL were 89.7% and 97.5%, respectively.
To define the accuracy of serum ceruloplasmin for the patients with acute liver failure, the ROC curve was constructed by using the data of 15 WD patients and 20 non-WD patients with acute liver failure. The area under the curve was 0.952 (95% confidence interval (CI), 0.885-1). The ROC curve indicated that the cutoff value of serum ceruloplasmin of 16 mg/dL gave the highest diagnostic accuracy for WD in the patients with acute liver failure (Fig. 2B).
To further define the accuracy of serum ceruloplasmin for diagnosis of WD in the patients with elevated aminotransferases, the ROC curve was constructed by using the data of 256 asymptomatic WD patients with elevated aminotransferases and 38 non-WD patients with viral hepatitis. The area under the curve was 0.994 (95% confidence interval (CI), 0.988-1). The ROC curve suggested that the cutoff value of serum ceruloplasmin of 16.85 mg/dL gave the highest diagnostic accuracy for WD with elevated aminotransferases (Fig. 2C).
As shown in Fig. 2D-F, the mean level of serum ceruloplasmin of 317 WD patients was 5.7 ± 4.7 mg/dL, significantly lower than that in all of 547 non-WD children (6.0 ± 4.0 mg/dL) (p < 0.001). For the patients with acute liver failure, the mean level of serum ceruloplasmin in WD patients (9.3 ± 4.7 mg/dL) was lower than that in non-WD patients (29.7 ± 14.3 mg/dL) (p < 0.001). In the situation with elevated aminotransferases, the mean level of serum ceruloplasmin in 249 asymptomatic WD patients (5.5 ± 4.7 mg/dL) was significantly lower than that in 38 patients with viral hepatitis (32.5 ± 7.9 mg/dL) (p < 0.001).