The rate of medullary thyroid carcinoma (MTC) among people with intermediate calcitonin levels, or with values between 10 and 100 pg/mL, is around 10% and “cannot be overlooked,” according to a new study published in the journal Reviews in Endocrine and Metabolic Disorders. Moreover, the risk of MTC significantly increases when calcitonin levels are above 20 pg/mL. 

“Therefore, clinicians, and endocrinologists first, should be aware of these issues,” the study authors wrote. “It is necessary that international guidelines take a position on routine [calcitonin] screening incorporating these concepts.”

Read more about MTC diagnosis

Continue Reading

Elevated calcitonin levels are the most accurate tool to diagnose MTC, the researchers noted. However, there are no recommendations to manage indeterminate calcitonin levels, they added. 

To identify the frequency of intermediate calcitonin among patients with thyroid nodules and the ratio of MTC among these patients, a team of researchers led by Pierpaolo Trimboli, MD, conducted a systematic review of the literature and metaanalysis.

The team identified 233 articles and quantitatively analyzed 15 of them. 

They found that a total of 29,533 people had had calcitonin testing. Of those, 1.7% had intermediate calcitonin levels, and 9.6% were diagnosed with MTC. 

The rate of MTC was significantly lower among people who had calcitonin levels between 10 and 20 pg/mL compared to those who had calcitonin levels between 20 and 100 pg/mL.

The researchers concluded that the ratio of people with thyroid nodules who have intermediate calcitonin levels is negligible. However, the rate of MTC among these people cannot be overlooked, especially for those with levels above 20 pg/mL.

MTC is a rare type of neuroendocrine tumor of the thyroid gland arising arises from the parafollicular or C cells. Early diagnosis is important as the disease can spread to the cervical lymph nodes and other parts of the body, including the lungs, brain, bones, and liver, if not treated on time.


Piticchio T, Frasca F, Trimboli P. Prevalence and significance of indeterminate calcitonin values in patients with thyroid nodules: a systematic review and meta-analysis. Rev Endocr Metab Disord. Published online May 31, 2023. doi:10.1007/s11154-023-09811-7