J Endocrinol Metab

Journal of Endocrinology and Metabolism, ISSN 1923-2861 print, 1923-287X online, Open Access

Article copyright, the authors; Journal compilation copyright, J Endocrinol Metab and Elmer Press Inc

Journal website http://www.jofem.org

Original Article

Volume 7, Number 1, February 2017, pages 5-17

Modified Fine-Needle Aspiration Biopsy for Calcitonin, Procalcitonin and Carcinoembryonic Antigen Levels in the Diagnosis of Thyroid Nodules With Medullary Thyroid Carcinoma

Figure 1. (Patient 1) (a) Results of FNB biopsy of the right thyroid nodules (two nodules, 1a and 1b biopsied together): follicular cells trying to form microfollicles. Follicular cells show some degree of atypia. These features suggest follicular lesions of undetermined significance (Diff-Quik, × 600). (b) Results of FNB biopsy of the left thyroid nodule (nodule 2a): follicular cells forming microfollicles. Follicular cells show some degree of atypia. These features suggest follicular lesions of undetermined significance (Diff-Quik, × 600). (c) Results of MFNB biopsy of the right thyroid nodules (two nodules, 1a and 1b biopsied together): cellular smears consisting of discohesive cells with abundant amphophillic cytoplasm, and eccentrically placed nuclei with prominent nucleoli. These features along with elevated serum calcitonin suggest medullary thyroid cancer (Diff-Quik, × 600). (d) MFNB of the left thyroid nodule (nodule 2a): amorphous material suggestive of amyloid material (Congo red stain not done) (Diff-Quik, × 600). (e) MFNB of the left thyroid nodule (nodule 2a): crowded groups of mildly enlarged cells with oval to focally spindled nuclei, moderate to abundant cytoplasm and finely stippled chromatin. While not classic for medullary carcinoma, the concurrent finding of elevated serum calcitonin makes the diagnosis more likely (Diff-Quik, × 600). (f) MFNB of the left thyroid nodule (nodule 2a): cells with oval to focally spindled nuclei, abundant cytoplasm and finely stippled chromatin. While not classic for medullary carcinoma, the concurrent finding of elevated serum calcitonin makes the diagnosis more likely (Diff-Quik, × 600). FNB: fine-needle biopsy; MFNB: modified fine-needle biopsy; Diff. quick: Diff quick stain.

Figure 2. (Patient 2) (a) Results of FNB biopsy of the right thyroid nodule: follicular cells forming microfollicles and showing some degree of atypia. These features suggest follicular lesions of undetermined significance (Diff-Quik, × 600). (b) Results of MFNB of right thyroid nodule: crowded groups of mildly enlarged cells with oval to focally spindled nuclei, moderate cytoplasm and finely stippled chromatin. While not classic for medullary carcinoma, the concurrent finding of elevated serum calcitonin makes this diagnosis more likely (Diff-Quik, × 600). FNB: fine-needle biopsy; MFNB: modified fine-needle biopsy; Diff. quick: Diff quick stain.

Figure 3. (Patient 3) (a) MFNB of the right thyroid nodule showing: cellular smears consisting of discohesive cells with abundant amphophillic cytoplasm, and eccentrically placed nuclei with prominent nucleoli (oncocytic features) (Diff-Quik, × 600). (b) MFNB of the left thyroid nodule: smears consisting of discohesive, focally enlarged cells with eccentric nuclei with occasional nucleoli, coarse chromatin and abundant cytoplasm. These features along with elevated serum calcitonin suggest medullary thyroid cancer (Diff-Quik, × 600). FNB: fine-needle biopsy; MFNB: modified fine-needle biopsy; Diff. quick: Diff quick stain.

**Table 1.** Serum Levels of Calcium, Calcitonin (Ct), Procalcitonin (PCt) and Carcinoembryonic Antigen (CEA) in Patients With Medullary Thyroid Cancer Following Intravenous Administration of Calcium Gluconate
Serum levels	Minutes post-calcium administration
Calcium gluconate (2.5 mg/kg) was administered intravenously over 1 min and blood samples were obtained at the indicated various time intervals as mentioned in “Methods” [22]. Reference values: basal serum Ct 0.0 - 8.4 pg/mL, basal PCt 0.00 - 0.50 ng/mL, CEA 0.2 - 4.7 ng/mL. The serum Ct threshold for the identification of MTC was defined a > 26 pg/mL for basal levels in females [22]. The threshold for calcium-stimulated Ct level was > 79 pg/mL in females [22]. The threshold for calcium-stimulated PCt level was > 1.65 ng/mL. The threshold for stimulated CEA was considered as 17.16 ng/mL.
Calcium (mg/dL)
Patient 1	9.5	10.6	11.1	10.7	9.6
Patient 2	9.9	11.6	11.2	10.8	9.8
Patient 3	9.0	10.4	10.9	10.9	9.4
Calcitonin (pg/mL)
Patient 1	41	555	642	889	718
Patient 2	58	78	142	123	82
Patient 3	69	439	320	184	98
Procalcitonin (ng/mL)
Patient 1	0.32	2.32	3.99	1.78	1.05
Patient 2	2.48	6.30	6.97	7.11	4.88
Patient 3	0.42	1.45	3.94	1.01	1.38
Carcinoembryonic antigen (ng/mL)
Patient 1	2.50	2.81	2.32	2.00	2.86
Patient 2	1.86	1.76	1.75	1.69	1.83
Patient 3	3.22	4.10	3.84	3.46	3.09

Table 1. Serum Levels of Calcium, Calcitonin (Ct), Procalcitonin (PCt) and Carcinoembryonic Antigen (CEA) in Patients With Medullary Thyroid Cancer Following Intravenous Administration of Calcium Gluconate

Serum levels

Minutes post-calcium administration

Calcium gluconate (2.5 mg/kg) was administered intravenously over 1 min and blood samples were obtained at the indicated various time intervals as mentioned in “Methods” [22]. Reference values: basal serum Ct 0.0 - 8.4 pg/mL, basal PCt 0.00 - 0.50 ng/mL, CEA 0.2 - 4.7 ng/mL. The serum Ct threshold for the identification of MTC was defined a > 26 pg/mL for basal levels in females [22]. The threshold for calcium-stimulated Ct level was > 79 pg/mL in females [22]. The threshold for calcium-stimulated PCt level was > 1.65 ng/mL. The threshold for stimulated CEA was considered as 17.16 ng/mL.

Calcium (mg/dL)

Patient 1

9.5

10.6

11.1

10.7

9.6

Patient 2

9.9

11.6

11.2

10.8

9.8

Patient 3

9.0

10.4

10.9

9.4

Calcitonin (pg/mL)

Patient 1

555

642

889

718

Patient 2

142

123

Patient 3

439

320

184

Procalcitonin (ng/mL)

Patient 1

0.32

2.32

3.99

1.78

1.05

Patient 2

2.48

6.30

6.97

7.11

4.88

Patient 3

0.42

1.45

3.94

1.01

1.38

Carcinoembryonic antigen (ng/mL)

Patient 1

2.50

2.81

2.32

2.00

2.86

Patient 2

1.86

1.76

1.75

1.69

1.83

Patient 3

3.22

4.10

3.84

3.46

3.09

**Table 2.** Calcitonin (Ct), Procalcitonin (PCt) and Carcinoembryonic Antigen (CEA) Levels in Serum and Fine-Needle Aspiration Biopsy (FNB) Samples in Patients With Medullary Thyroid Cancer
Tumor markers	Serum	FNB aspirate
Levels of Ct, PCt and CEA, in fine-needle aspirates (FNB) were determined as mentioned in “Methods”. Blood was drawn just prior to performing FNB for the determination of serum levels of Ct, PCt and CEA. Patient 1 had three nodules and all three nodules were biopsied. Rt thyroid nodule, 1a and the adjacent second Rt nodule, 1b were biopsied together and considered as a single aspirate sample as mentioned in “Methods”. In this patient, Lt thyroid nodule, 2a was also biopsied. In patient 2, the right lobe nodule,1a was biopsied. Patient 3 had bilateral thyroid nodules which were biopsied (Rt thyroid nodule,1a Lt thyroid nodule, 2b) as outlined in “Methods”. Reference ranges: basal serum Ct 0.0 - 8.4 pg/mL, basal PCt 0.00 - 0.50 ng/mL, CEA 0.2 - 4.7 ng/mL. The basal serum Ct threshold for the identification of MTC was defined as > 26 pg/mL for females [22]. The threshold for calcium-stimulated Ct level of > 1,000 pg/mL in needle biopsy samples was considered diagnostic for MTC [24]. The diagnostic values for FNB aspirate samples for PCt and CEA were > 2.0 and > 18 ng/mL, respectively.
Calcitonin (pg/mL)
Patient 1	48	726 (Rt thyroid nodule-1a and 1b) 824 (Lt thyroid nodule-2a)
Patient 2	52	1,996 (Rt thyroid nodule-1a)
Patient 3	70	744 (Rt thyroid nodule-1a) 1,120 (Lt thyroid nodule-2a)
Procalcitonin (ng/mL)
Patient 1	0.92	1.6 (Rt thyroid nodule-1a and 1b) 2.0 (Lt thyroid nodule-2a)
Patient 2	3.2	4.4 (Rt thyroid nodule-1a)
Patient 3	0.61	1.8 (Rt thyroid nodule-1a) 8.0 (Lt thyroid nodule-2b)
Carcinoembryonic antigen (ng/mL)
Patient 1	2.9	13.9 (Rt thyroid nodule-1a and 1b) 14.2 (Lt thyroid nodule-2a)
Patient 2	166	21.6 (Rt thyroid nodule-1a)
Patient 3	4	17.7 (Rt thyroid nodule-1a) 19.6 (Lt thyroid nodule-2b)

Table 2. Calcitonin (Ct), Procalcitonin (PCt) and Carcinoembryonic Antigen (CEA) Levels in Serum and Fine-Needle Aspiration Biopsy (FNB) Samples in Patients With Medullary Thyroid Cancer

Tumor markers

Serum

FNB aspirate

Levels of Ct, PCt and CEA, in fine-needle aspirates (FNB) were determined as mentioned in “Methods”. Blood was drawn just prior to performing FNB for the determination of serum levels of Ct, PCt and CEA. Patient 1 had three nodules and all three nodules were biopsied. Rt thyroid nodule, 1a and the adjacent second Rt nodule, 1b were biopsied together and considered as a single aspirate sample as mentioned in “Methods”. In this patient, Lt thyroid nodule, 2a was also biopsied. In patient 2, the right lobe nodule,1a was biopsied. Patient 3 had bilateral thyroid nodules which were biopsied (Rt thyroid nodule,1a Lt thyroid nodule, 2b) as outlined in “Methods”. Reference ranges: basal serum Ct 0.0 - 8.4 pg/mL, basal PCt 0.00 - 0.50 ng/mL, CEA 0.2 - 4.7 ng/mL. The basal serum Ct threshold for the identification of MTC was defined as > 26 pg/mL for females [22]. The threshold for calcium-stimulated Ct level of > 1,000 pg/mL in needle biopsy samples was considered diagnostic for MTC [24]. The diagnostic values for FNB aspirate samples for PCt and CEA were > 2.0 and > 18 ng/mL, respectively.

Calcitonin (pg/mL)

Patient 1

726 (Rt thyroid nodule-1a and 1b)
824 (Lt thyroid nodule-2a)

Patient 2

1,996 (Rt thyroid nodule-1a)

Patient 3

744 (Rt thyroid nodule-1a)
1,120 (Lt thyroid nodule-2a)

Procalcitonin (ng/mL)

Patient 1

0.92

1.6 (Rt thyroid nodule-1a and 1b)
2.0 (Lt thyroid nodule-2a)

Patient 2

3.2

4.4 (Rt thyroid nodule-1a)

Patient 3

0.61

1.8 (Rt thyroid nodule-1a)
8.0 (Lt thyroid nodule-2b)

Carcinoembryonic antigen (ng/mL)

Patient 1

2.9

13.9 (Rt thyroid nodule-1a and 1b)
14.2 (Lt thyroid nodule-2a)

Patient 2

166

21.6 (Rt thyroid nodule-1a)

Patient 3

17.7 (Rt thyroid nodule-1a)
19.6 (Lt thyroid nodule-2b)

**Table 3.** Calcitonin (Ct), Procalcitonin (PCt) and Carcinoembryonic Antigen (CEA) Levels in Serum and Modified Fine-Needle Aspiration Biopsy (MFNB) Samples in Patients With Medullary Thyroid Cancer
Tumor markers	Serum	MFNB aspirate
Levels of Ct, PCt and CEA, in modified fine-needle aspirates (MFNB) were determined as mentioned in “Methods”. Blood was drawn just prior to performing MFNB for the determination of serum levels of Ct, PCt and CEA. Patient 1 had three nodules and all three nodules were biopsied. Rt thyroid nodule, 1a and the adjacent second Rt nodule, 1b were biopsied together and considered as a single aspirate sample as mentioned in “Methods”. In this patient, Lt thyroid nodule, 2a was also biopsied. In patient 2, the right lobe nodule, 1a was biopsied. Patient 3 had bilateral thyroid nodules which were biopsied (Rt thyroid nodule, 1a and Lt thyroid nodule, 2b) as outlined in “Methods”. Reference ranges: basal serum Ct 0.0 - 8.4 pg/mL, basal PCt 0.00 - 0.50 ng/mL, CEA 0.2 - 4.7 ng/mL. The basal serum Ct threshold for the identification of MTC was defined as > 26 pg/mL for females [22]. The threshold for Ct level of > 1,000 pg/mL in needle biopsy samples was considered diagnostic for MTC [24]. The diagnostic values for MFNB aspirate samples for PCt and CEA were > 2.0 and > 18 ng/mL.
Calcitonin (pg/mL)
Patient 1	52	1,036 (Rt thyroid nodules-1a and 1b) 1,870 (Lt thyroid nodule-2a)
Patient 2	68	1,440 (Rt thyroid nodule-1a)
Patient 3	82	1,341 (Rt thyroid nodule-1a) 1,328 (Lt thyroid nodule-2a)
Procalcitonin (ng/mL)
Patient 1	0.48	3.2 (Rt thyroid nodule-1a and 1b) 2.8 (Lt thyroid nodule-2a)
Patient 2	2.40	7.8 (Rt thyroid nodule 1a)
Patient 3	0.43	6.8 (Rt thyroid nodule-1a) 9.2 (Lt thyroid nodule-2b)
Carcinoembryonic antigen (ng/mL)
Patient 1	3.1	21.9 (Rt thyroid nodule (1a and 1b) 18.6 (Lt thyroid nodule-2a)
Patient 2	170	29.9 (Rt thyroid nodule-1a)
Patient 3	3.6	52.3 (Rt thyroid nodule-1a) 28.1 (Lt thyroid nodule-2b)

Table 3. Calcitonin (Ct), Procalcitonin (PCt) and Carcinoembryonic Antigen (CEA) Levels in Serum and Modified Fine-Needle Aspiration Biopsy (MFNB) Samples in Patients With Medullary Thyroid Cancer

Tumor markers

Serum

MFNB aspirate

Levels of Ct, PCt and CEA, in modified fine-needle aspirates (MFNB) were determined as mentioned in “Methods”. Blood was drawn just prior to performing MFNB for the determination of serum levels of Ct, PCt and CEA. Patient 1 had three nodules and all three nodules were biopsied. Rt thyroid nodule, 1a and the adjacent second Rt nodule, 1b were biopsied together and considered as a single aspirate sample as mentioned in “Methods”. In this patient, Lt thyroid nodule, 2a was also biopsied. In patient 2, the right lobe nodule, 1a was biopsied. Patient 3 had bilateral thyroid nodules which were biopsied (Rt thyroid nodule, 1a and Lt thyroid nodule, 2b) as outlined in “Methods”. Reference ranges: basal serum Ct 0.0 - 8.4 pg/mL, basal PCt 0.00 - 0.50 ng/mL, CEA 0.2 - 4.7 ng/mL. The basal serum Ct threshold for the identification of MTC was defined as > 26 pg/mL for females [22]. The threshold for Ct level of > 1,000 pg/mL in needle biopsy samples was considered diagnostic for MTC [24]. The diagnostic values for MFNB aspirate samples for PCt and CEA were > 2.0 and > 18 ng/mL.

Calcitonin (pg/mL)

Patient 1

1,036 (Rt thyroid nodules-1a and 1b)
1,870 (Lt thyroid nodule-2a)

Patient 2

1,440 (Rt thyroid nodule-1a)

Patient 3

1,341 (Rt thyroid nodule-1a)
1,328 (Lt thyroid nodule-2a)

Procalcitonin (ng/mL)

Patient 1

0.48

3.2 (Rt thyroid nodule-1a and 1b)
2.8 (Lt thyroid nodule-2a)

Patient 2

2.40

7.8 (Rt thyroid nodule 1a)

Patient 3

0.43

6.8 (Rt thyroid nodule-1a)
9.2 (Lt thyroid nodule-2b)

Carcinoembryonic antigen (ng/mL)

Patient 1

3.1

21.9 (Rt thyroid nodule (1a and 1b)
18.6 (Lt thyroid nodule-2a)

Patient 2

170

29.9 (Rt thyroid nodule-1a)

Patient 3

3.6

52.3 (Rt thyroid nodule-1a)
28.1 (Lt thyroid nodule-2b)

**Table 4.** Serum Levels of Calcium, Calcitonin (Ct), Procalcitonin (PCt) and Carcinoembryonic Antigen (CEA) in Patients With Benign Thyroid Nodules (n = 3, Patients 1, 2 and 4) and Multifocal Papillary Thyroid Cancer (n = 1, Patient 3) Following Intravenous Administration of Calcium Gluconate
Serum levels	Minutes post-calcium stimulation
Calcium gluconate (2.5 mg/kg) was administered intravenously over 1 min and blood samples were obtained at the indicated various time intervals as mentioned in “Methods”. Reference ranges: basal serum Ct 0.0 - 8.4 pg/mL, basal PCt 0.00 - 0.50 ng/mL, CEA 0.2 - 4.7 ng/mL. The serum Ct threshold for the identification of MTC was defined as > 26 pg/mL for basal levels in females [22]. The threshold for calcium-stimulated Ct levels was > 79 pg/mL in females [22]. In this study, the basal serum threshold for PCt was defined as > 0.5 ng/mL and the threshold for calcium-stimulated abnormal PCt level was defined as > 1.65 ng/mL. The threshold for basal CEA was > 5.0 ng/mL and the threshold for stimulated CEA was considered as 17.16 ng/mL.
Calcium (mg/dL)
Patient 1	8.6	10.1	10.0	9.1	9.3
Patient 2	9.2	10.4	10.3	9.4	9.6
Patient 3	8.6	10.0	9.6	9.6	9.5
Patient 4	8.9	10.6	10.1	9.8	9.4
Calcitonin (pg/mL)
Patient 1	30	125	88	47	30
Patient 2	39	112	97	58	44
Patient 3	2.9	36	24	17	4.2
Patient 4	27	56	48	42	22
Procalcitonin (pg/mL)
Patient 1	0.14	0.15	0.13	0.12	0.13
Patient 2	0.05	0.05	0.005	0.05	0.05
Patient 3	0.16	0.13	0.15	0.17	0.18
Patient 4	0.18	0.10	0.05	0.05	0.05
Carcinoembryonic antigen (ng/mL)
Patient 1	0.24	0.23	0.20	0.25	0.21
Patient 2	1.6	1.5	1.6	1.5	1.5
Patient 3	1.7	1.6	1.2	1.4	1.5
Patient 4	0.8	0.9	1.0	0.45	0.67

Table 4. Serum Levels of Calcium, Calcitonin (Ct), Procalcitonin (PCt) and Carcinoembryonic Antigen (CEA) in Patients With Benign Thyroid Nodules (n = 3, Patients 1, 2 and 4) and Multifocal Papillary Thyroid Cancer (n = 1, Patient 3) Following Intravenous Administration of Calcium Gluconate

Serum levels

Minutes post-calcium stimulation

Calcium gluconate (2.5 mg/kg) was administered intravenously over 1 min and blood samples were obtained at the indicated various time intervals as mentioned in “Methods”. Reference ranges: basal serum Ct 0.0 - 8.4 pg/mL, basal PCt 0.00 - 0.50 ng/mL, CEA 0.2 - 4.7 ng/mL. The serum Ct threshold for the identification of MTC was defined as > 26 pg/mL for basal levels in females [22]. The threshold for calcium-stimulated Ct levels was > 79 pg/mL in females [22]. In this study, the basal serum threshold for PCt was defined as > 0.5 ng/mL and the threshold for calcium-stimulated abnormal PCt level was defined as > 1.65 ng/mL. The threshold for basal CEA was > 5.0 ng/mL and the threshold for stimulated CEA was considered as 17.16 ng/mL.

Calcium (mg/dL)

Patient 1

8.6

10.1

10.0

9.1

9.3

Patient 2

9.2

10.4

10.3

9.4

9.6

Patient 3

8.6

10.0

9.6

9.5

Patient 4

8.9

10.6

10.1

9.8

9.4

Calcitonin (pg/mL)

Patient 1

125

Patient 2

112

Patient 3

2.9

4.2

Patient 4

Procalcitonin (pg/mL)

Patient 1

0.14

0.15

0.13

0.12

0.13

Patient 2

0.05

0.005

0.05

Patient 3

0.16

0.13

0.15

0.17

0.18

Patient 4

0.18

0.10

0.05

Carcinoembryonic antigen (ng/mL)

Patient 1

0.24

0.23

0.20

0.25

0.21

Patient 2

1.6

1.5

1.6

1.5

Patient 3

1.7

1.6

1.2

1.4

1.5

Patient 4

0.8

0.9

1.0

0.45

0.67

**Table 5.** Calcitonin (Ct), Procalcitonin (PCt), and Carcinoembryonic Antigen (CEA) in Serum and Modified Find-Needle Aspiration Biopsy (MFNB) Samples in Benign Thyroid Nodules (n = 3, Patients 1 - 3) and in Another Patient (Patient 4) With Subcentimeter Multicentric Papillary Thyroid Cancer
	Serum	MFNB aspirate
Blood was drawn for the determination of Ct, PCt, and CEA levels just prior to performing MFNB. In patients 1 - 3 only MFNB was performed and the aspirate results are shown above. In patient 4, initially FNB was performed which showed abnormal cells suggestive of follicular neoplasm and in this patient the FNB aspirate samples showed low values of Ct, PCt, and CEA (data not shown). In this patient MFNB was performed subsequently and the cytology report was consistent with papillary thyroid cancer and the MFNB results are shown in this Table. Reference ranges: basal serum Ct 0.0 - 8.4 pg/mL, basal PCt 0.00 - 0.50 ng/mL, CEA 0.2 - 4.7 ng/mL. The MTC diagnostic value for basal serum Ct level was > 26 pg/mL for females [22]. In this study, the basal serum threshold for PCt was defined as > 0.5 ng/mL and for CEA this value was > 5.0 ng/mL. The threshold for Ct level of > 1,000 pg/mL in needle biopsy samples was considered diagnostic for MTC [24]. The diagnostic values for MFNB aspirate samples for PCt and CEA were > 2.0 and > 18 ng/mL, respectively.
Calcitonin (pg/mL)
Patient 1	28	3.2
Patient 2	44	< 0.05
Patient 3	4.7	1.9
Patient 4	33	2.7
Procalcitonin (ng/mL)
Patient 1	0.12	0.22
Patient 2	0.41	0.43
Patient 3	0.36	0.19
Patient 4	0.18	0.38
Carcinoembryonic antigen (ng/mL)
Patient 1	2.9	3.7
Patient 2	2.2	2.4
Patient 3	1.3	3.2
Patient 4	4.1	3.6

Table 5. Calcitonin (Ct), Procalcitonin (PCt), and Carcinoembryonic Antigen (CEA) in Serum and Modified Find-Needle Aspiration Biopsy (MFNB) Samples in Benign Thyroid Nodules (n = 3, Patients 1 - 3) and in Another Patient (Patient 4) With Subcentimeter Multicentric Papillary Thyroid Cancer

Serum

MFNB aspirate

Blood was drawn for the determination of Ct, PCt, and CEA levels just prior to performing MFNB. In patients 1 - 3 only MFNB was performed and the aspirate results are shown above. In patient 4, initially FNB was performed which showed abnormal cells suggestive of follicular neoplasm and in this patient the FNB aspirate samples showed low values of Ct, PCt, and CEA (data not shown). In this patient MFNB was performed subsequently and the cytology report was consistent with papillary thyroid cancer and the MFNB results are shown in this Table. Reference ranges: basal serum Ct 0.0 - 8.4 pg/mL, basal PCt 0.00 - 0.50 ng/mL, CEA 0.2 - 4.7 ng/mL. The MTC diagnostic value for basal serum Ct level was > 26 pg/mL for females [22]. In this study, the basal serum threshold for PCt was defined as > 0.5 ng/mL and for CEA this value was > 5.0 ng/mL. The threshold for Ct level of > 1,000 pg/mL in needle biopsy samples was considered diagnostic for MTC [24]. The diagnostic values for MFNB aspirate samples for PCt and CEA were > 2.0 and > 18 ng/mL, respectively.

Calcitonin (pg/mL)

Patient 1

3.2

Patient 2

< 0.05

Patient 3

4.7

1.9

Patient 4

2.7

Procalcitonin (ng/mL)

Patient 1

0.12

0.22

Patient 2

0.41

0.43

Patient 3

0.36

0.19

Patient 4

0.18

0.38

Carcinoembryonic antigen (ng/mL)

Patient 1

2.9

3.7

Patient 2

2.2

2.4

Patient 3

1.3

3.2

Patient 4

4.1

3.6