Nontoxic Goiter (ICD-11: 5A01): Complete Coding and Diagnostic Guide

1. Introduction

Nontoxic goiter represents a volumetric enlargement of the thyroid gland that occurs without alterations in hormonal production, characterized by the absence of hyperthyroidism or thyrotoxicosis. This condition results primarily from follicular multiplication, a process in which the cells that compose thyroid follicles reproduce, leading to glandular growth without significant functional impairment.

The clinical importance of nontoxic goiter lies both in its prevalence and in its diagnostic and therapeutic implications. It is one of the most frequent thyroid alterations in worldwide medical practice, affecting populations of different age groups, with predominance in women and in regions with specific geographic and nutritional characteristics. Glandular growth can vary from discrete increases, detectable only by imaging studies, to voluminous masses that cause compressive symptoms and significant aesthetic alterations.

From a public health perspective, nontoxic goiter represents an important challenge, especially in areas with endemic iodine deficiency, where food fortification programs play a fundamental preventive role. The socioeconomic impact includes costs with diagnostic investigation, prolonged clinical follow-up, and in selected cases, surgical treatment or radioiodine therapy.

Correct coding of this condition is critical for multiple aspects of healthcare: it enables appropriate epidemiological tracking, facilitates prevalence and incidence studies, ensures appropriate reimbursement in health systems, enables analysis of therapeutic outcomes, and guarantees continuity of care among different professionals and institutions. The transition to ICD-11 brought greater specificity in the classification of thyroid disorders, making it essential that healthcare professionals understand the nuances of nontoxic goiter coding.

2. Correct ICD-11 Code

Code: 5A01

Description: Nontoxic goiter

Parent category: Disorders of thyroid gland or thyroid hormone system

Official definition: Enlargement of the thyroid gland due to follicular multiplication, unaccompanied by hyperthyroidism or thyrotoxicosis.

This code belongs to chapter 5 of ICD-11, which covers diseases of the endocrine, nutritional, or metabolic system. The classification 5A01 is specific for situations in which there is confirmed thyroid enlargement without associated hormonal dysfunction. The definition emphasizes two fundamental criteria: first, the presence of glandular growth documented by physical examination or imaging methods; second, the absence of functional alterations that would characterize hyperthyroidism or thyrotoxicosis.

The parent category groups all disorders related to the thyroid gland, allowing a logical organization that facilitates navigation among related codes. Code 5A01 has three subcategories that allow greater diagnostic specificity when applicable, reflecting different morphological presentations of nontoxic goiter. Additionally, there are six related codes that represent conditions that should be differentiated or that may coexist with nontoxic goiter.

The hierarchical structure of ICD-11 allows this code to be used both independently and in conjunction with extension specifiers, which can detail aspects such as laterality, severity, or specific morphological characteristics, when clinically relevant and documented.

3. When to Use This Code

Code 5A01 should be used in specific clinical scenarios where there is unequivocal confirmation of thyroid enlargement without hormonal dysfunction. Below, we present detailed practical situations:

Scenario 1: Diffuse euthyroid goiter detected on routine examination A 45-year-old female patient presents for routine consultation and during physical examination diffuse and symmetric thyroid enlargement is identified, with a gland of elastic consistency, smooth surface, and no palpable nodules. Laboratory investigation reveals TSH, free T4, and T3 within reference values. Ultrasonography confirms diffuse volumetric enlargement without nodules. This is the classic scenario for using code 5A01, characterizing non-toxic diffuse goiter.

Scenario 2: Euthyroid multinodular goiter A 60-year-old patient presents with thyroid enlargement detected several years ago, with slow progressive growth. On physical examination, an enlarged gland with multiple palpable nodules bilaterally is identified. Thyroid function is preserved, with normal TSH and absence of thyrotoxicosis symptoms. Ultrasonography demonstrates multiple nodules in both lobes. Fine needle aspiration cytology (FNAC) of the larger nodules reveals benign cytology. In this case, code 5A01 is appropriate, and may be specified as non-toxic multinodular goiter.

Scenario 3: Uninodular goiter without hyperfunction Patient notices localized enlargement in the anterior cervical region. Evaluation reveals a single thyroid nodule of 3 centimeters in the right lobe, with normal thyroid function. Scintigraphy demonstrates a normocaptant nodule (non-autonomous). FNAC indicates follicular adenoma. This presentation justifies the use of code 5A01 for non-toxic uninodular goiter.

Scenario 4: Goiter with compressive symptoms but preserved function Patient reports mild dysphagia and sensation of cervical fullness. Examination reveals voluminous goiter with partial retrosternal extension. Despite significant volume, laboratory tests demonstrate normal thyroid function. Computed tomography confirms intrathoracic extension without signs of malignancy. Code 5A01 is appropriate, as the presence of compressive symptoms does not exclude the diagnosis of non-toxic goiter when function is preserved.

Scenario 5: Follow-up of previously diagnosed goiter Patient under regular follow-up for non-toxic goiter for five years, maintaining stable thyroid function and no significant growth documented by serial ultrasonographies. At follow-up consultations, code 5A01 remains appropriate as long as there is no development of hormonal dysfunction or other complications.

Scenario 6: Goiter detected in investigation of nonspecific symptoms Patient investigates fatigue and discrete weight gain. During evaluation, moderate thyroid enlargement is detected. Hormonal tests are normal, ruling out hypothyroidism as the cause of symptoms. Code 5A01 adequately documents the thyroid finding, even if it does not explain the initial symptomatology.

4. When NOT to Use This Code

Inappropriate use of code 5A01 can occur when important exclusion criteria are not observed. It is fundamental to differentiate nontoxic goiter from other thyroid conditions:

Specific exclusions by alternative codes:

When goiter is of congenital origin, specific codes should be used. If the patient presents with congenital diffuse goiter, the appropriate code is 234769120, not 5A01. Similarly, congenital goiter not otherwise specified (NOS) should also be coded as 234769120. Congenital parenchymatous goiter requires code 1357352994. The fundamental distinction lies in the age of onset and etiology: congenital goiters manifest from birth or early years of life and are frequently associated with defects in hormone synthesis.

When thyroid enlargement is directly related to iodine deficiency, especially in endemic contexts with epidemiological documentation of this deficiency, code 234769120 is more appropriate, as it captures the specific etiology. Code 5A01 is more suitable for sporadic goiters or when iodine deficiency is not the predominant causal factor.

Other exclusion situations:

Do not use code 5A01 when there is evidence of thyroid dysfunction. If laboratory tests demonstrate suppressed TSH or elevation of free thyroid hormones, even if the patient does not yet present evident clinical symptoms, the diagnosis of nontoxic goiter does not apply. In these cases, codes related to hyperthyroidism or thyrotoxicosis are necessary.

When there is evidence of acute or subacute inflammatory process of the thyroid, with pain, local tenderness, and elevated inflammatory markers, the diagnosis is thyroiditis, not nontoxic goiter. Autoimmune processes such as Hashimoto's thyroiditis, even when still in the euthyroid phase, have specific coding and should not be classified as 5A01.

Malignant lesions of the thyroid, even when presenting with glandular growth, require specific oncological codes. Suspicion or confirmation of malignancy completely excludes the use of code 5A01.

Simple thyroid cysts, without significant follicular proliferation, do not fit the definition of nontoxic goiter and have their own coding.

5. Step-by-Step Coding Process

Step 1: Assess diagnostic criteria

Confirmation of nontoxic goiter diagnosis requires a systematic approach. Begin with detailed clinical history, investigating duration of evolution, compressive symptoms (dysphagia, dyspnea, hoarseness), family history of thyroid disease, radiation exposure, use of goitrogenic medications, and geographic origin.

Physical examination should include cervical inspection with the neck in slight extension, systematic palpation of the gland with the examiner positioned posteriorly to the patient, assessment of characteristics such as size, consistency, surface, presence of nodules, mobility with swallowing, and presence of cervical lymphadenopathy. Size classification may follow World Health Organization criteria.

Essential diagnostic instruments include hormonal assays (TSH as initial test, followed by free T4 and total or free T3 if TSH is altered), cervical ultrasound with Doppler (documents glandular volume, echogenicity, presence and characteristics of nodules), and possibly thyroid scintigraphy when autonomous areas are suspected. Fine needle aspiration puncture is indicated for nodules with suspicious ultrasound characteristics.

Step 2: Verify specifiers

After confirming the diagnosis, determine the specific characteristics of the goiter. Classify according to morphology: diffuse (homogeneous enlargement without nodules), uninodular (single dominant nodule), or multinodular (multiple nodules).

Assess severity based on glandular volume (mild, moderate, or severe), presence of compressive symptoms, and aesthetic impact. Document duration when known (recent versus long-standing).

Identify additional characteristics such as presence of calcifications, increased vascularization on Doppler, retrosternal extension, or substernal extension. This information, although not necessarily changing the main code, is important for therapeutic planning and prognosis.

Step 3: Differentiate from other codes

5A00 - Hypothyroidism: The fundamental difference lies in thyroid function. In hypothyroidism, there is elevated TSH and/or reduced free T4, with symptoms such as fatigue, weight gain, cold intolerance, and bradycardia. Goiter may be present in hypothyroidism (especially in Hashimoto's thyroiditis), but hormonal dysfunction characterizes code 5A00. In nontoxic goiter (5A01), function is preserved with normal TSH and thyroid hormones.

5A02 - Thyrotoxicosis: Characterized by excess circulating thyroid hormones, with suppressed TSH and elevation of free T4 and/or T3. Symptoms include weight loss, tachycardia, tremors, heat intolerance, and anxiety. Even if there is associated goiter (as in diffuse toxic goiter or multinodular toxic goiter), the presence of hyperfunction determines code 5A02. Code 5A01 explicitly requires absence of thyrotoxicosis.

5A03 - Thyroiditis NOS: Refers to inflammatory processes of the thyroid without further specification. It differs from nontoxic goiter by the presence of an inflammatory component, which may manifest as pain, local tenderness, fever (in acute forms), elevation of inflammatory markers, and frequently transient thyroid dysfunction. Nontoxic goiter does not present significant inflammatory characteristics.

Step 4: Required documentation

For adequate coding, the medical record must contain:

Mandatory checklist:

Description of physical examination of the thyroid (size, consistency, presence of nodules)
TSH results and, ideally, free T4
Thyroid ultrasound report with volumetric measurements
Exclusion of signs and symptoms of hyper- or hypothyroidism
When applicable, results of scintigraphy and FNAP
Duration of the condition
Compressive symptoms present or absent

The record should be clear regarding the absence of hormonal dysfunction, a central element in the definition of nontoxic goiter. Terms such as "euthyroid," "preserved thyroid function," or "without thyrotoxicosis" reinforce the appropriateness of code 5A01.

6. Complete Practical Example

Clinical Case

A 52-year-old female patient, a teacher, presents to the consultation reporting perception of neck enlargement noted approximately two years ago, with slow progressive growth. She denies symptoms such as palpitations, tremors, weight loss, heat intolerance, anxiety or irritability. She also denies excessive fatigue, significant weight gain, constipation or cold intolerance. She reports mild sensation of tightness in the neck when wearing closed collars, but without dysphagia, dysphonia or dyspnea. Positive family history for thyroid disease: mother underwent surgery for multinodular goiter at age 65. No history of radiation exposure. Denies medication use. From a region without known endemic iodine deficiency.

On physical examination, patient in good general condition, heart rate of 76 bpm, blood pressure 120/80 mmHg. Absence of exophthalmos, fine tremor of extremities or other manifestations of thyrotoxicosis. Skin with normal texture and moisture. On cervical examination, diffuse enlargement of the thyroid gland is identified, estimated at grade II, with slightly irregular surface on palpation, suggesting presence of small nodules, firm-elastic consistency, mobile on swallowing, painless, without audible murmurs. No palpable cervical lymphadenopathy.

Laboratory tests requested: TSH 2.1 mIU/L (reference: 0.4-4.0), free T4 1.2 ng/dL (reference: 0.8-1.8), total T3 110 ng/dL (reference: 80-180). Antithyroperoxidase antibodies (anti-TPO) negative. Cervical ultrasound demonstrates enlarged thyroid volume (right lobe: 6.2 x 2.8 x 2.5 cm; left lobe: 5.8 x 2.6 x 2.3 cm; total estimated volume of 32 mL, normal up to 18 mL for women), heterogeneous echotexture with multiple bilateral solid nodules, the largest measuring 1.8 cm in the right lobe, with low-risk ultrasound characteristics (isoechoic, regular margins, without microcalcifications, height/width ratio less than 1). Preserved vascularization on Doppler, without significant hypervascularization.

Fine needle aspiration biopsy of the largest nodule was performed, with cytological result Bethesda II (benign), compatible with colloid nodule.

Step-by-Step Coding

Analysis of criteria:

Presence of thyroid enlargement: Clinically confirmed (grade II) and by ultrasound (volume of 32 mL, almost double the upper normal limit).
Follicular multiplication: Evidenced by the presence of multiple nodules and diffuse volumetric increase, with cytology confirming benign nature (colloid nodule).
Absence of hyperthyroidism: Normal TSH (2.1 mIU/L), free T4 and T3 within reference values, without clinical symptoms of thyrotoxicosis.
Absence of thyrotoxicosis: No laboratory or clinical evidence of excess thyroid hormones.
Exclusion of other conditions: No characteristics of thyroiditis (absence of pain, inflammation or positive antibodies), not congenital (onset in adulthood), no evidence of malignancy (benign cytology).

Code chosen: 5A01 - Nontoxic goiter

Complete justification:

The case meets all criteria for nontoxic goiter: glandular enlargement documented clinically and by imaging, preserved thyroid function with normal TSH and free hormones, absence of symptoms of hormonal dysfunction, and exclusion of inflammatory, congenital or malignant processes. The multinodular morphology does not alter the main code 5A01, and can be specified in subcategory if the system allows for greater detail (nontoxic multinodular goiter).

Complementary codes:

In this specific case, there is no need for additional codes, as there are no documented thyroid comorbidities or complications. If there were significant compressive symptoms or retrosternal extension, extension codes could be considered according to the ICD-11 structure used in the registration system.

7. Related Codes and Differentiation

Within the Same Category

5A00 - Hypothyroidism

When to use: Use code 5A00 when there is laboratory evidence of thyroid hormone deficiency, characterized by elevated TSH (usually above 4.0-5.0 mIU/L) and/or reduced free T4. Clinically, the patient may present with fatigue, weight gain, bradycardia, constipation, dry skin, brittle hair, cold intolerance, and cognitive slowing.

Main difference vs. 5A01: The fundamental difference lies in thyroid function. In hypothyroidism (5A00), there is dysfunction with reduced hormone production, whereas in nontoxic goiter (5A01), function is preserved. It is important to note that goiter may be associated with hypothyroidism (especially in Hashimoto thyroiditis), but the presence of hormonal dysfunction determines coding as 5A00, not 5A01.

5A02 - Thyrotoxicosis

When to use: Code 5A02 is appropriate when there is excess circulating thyroid hormone, manifested by suppressed TSH (usually below 0.1 mIU/L) and elevation of free T4 and/or T3. Clinical symptoms include weight loss despite preserved or increased appetite, tachycardia, palpitations, fine tremor of extremities, excessive sweating, heat intolerance, anxiety, irritability, and insomnia.

Main difference vs. 5A01: Thyrotoxicosis is characterized by glandular hyperfunction with hormone excess, whereas nontoxic goiter maintains normal function. A goiter may become toxic (toxic multinodular goiter or Plummer disease), a situation in which the code changes from 5A01 to 5A02. The definition of nontoxic goiter explicitly excludes the presence of thyrotoxicosis.

5A03 - Thyroiditis NOS

When to use: Use 5A03 for inflammatory processes of the thyroid without additional specification of type. May include acute thyroiditis (bacterial, rare), subacute (De Quervain, often post-viral), or chronic when not specified. Characteristics include anterior cervical pain, tenderness on palpation, possible fever, elevation of inflammatory markers, and frequently transient thyroid dysfunction (initial hyperthyroid phase followed by hypothyroid phase).

Main difference vs. 5A01: Thyroiditis involves glandular inflammation, whereas nontoxic goiter results from follicular proliferation without significant inflammatory component. Clinically, pain and tenderness on palpation are characteristic of thyroiditis but absent in nontoxic goiter. Laboratorially, elevated inflammatory markers and transient hormonal dysfunction suggest thyroiditis, not nontoxic goiter.

Differential Diagnoses

Various conditions may present with thyroid enlargement and should be differentiated:

Graves disease: Characterized by autoimmune thyrotoxicosis with positive anti-TSH receptor antibodies, frequently associated with ophthalmopathy and dermopathy. The goiter is diffuse and hypervascularized, with increased and diffuse uptake on scintigraphy.

Toxic adenoma: Single hyperfunctioning nodule that causes thyrotoxicosis, with increased focal uptake on scintigraphy and suppression of the remaining parenchyma.

Thyroid carcinoma: May present as a nodule or glandular enlargement, but with suspicious ultrasound characteristics (hypoechogenicity, microcalcifications, central vascularization, irregular margins) and cytology suggestive of or confirming malignancy.

Hashimoto thyroiditis: Autoimmune disease with positive anti-TPO and/or antithyroglobulin antibodies, potentially causing goiter with heterogeneous echotexture. Frequently progresses to hypothyroidism.

8. Differences with ICD-10

In ICD-10, nontoxic goiter is coded primarily as E04, with subdivisions: E04.0 (nontoxic diffuse goiter), E04.1 (nontoxic uninodular goiter), E04.2 (nontoxic multinodular goiter), and E04.9 (nontoxic goiter, unspecified).

The main change in ICD-11 with code 5A01 is in the hierarchical structure and the possibility of greater specification through subcategories and extensions. ICD-11 offers a more logical organization, grouping thyroid disorders in a more intuitive manner and allowing more precise coding of specific clinical characteristics.

Another important difference is the clearer definition in ICD-11, which explicitly emphasizes follicular multiplication as the mechanism and the absence of both hyperthyroidism and thyrotoxicosis, making the inclusion and exclusion criteria more objective.

ICD-11 also facilitates the transition between codes when there is evolution of the clinical presentation. For example, a patient initially coded as 5A01 (nontoxic goiter) who develops hyperfunction can be easily reclassified to the appropriate code for thyrotoxicosis, with the ICD-11 structure making these relationships more transparent.

From a practical standpoint, health information systems that migrate from ICD-10 to ICD-11 should adequately map codes E04.x to 5A01 and its subcategories, ensuring continuity in epidemiological and administrative records. The greater specificity of ICD-11 may initially require adaptation by professionals, but tends to improve the quality of health data in the medium and long term.

9. Frequently Asked Questions

How is nontoxic goiter diagnosed?

The diagnosis combines clinical and laboratory evaluation. It begins with careful physical examination of the thyroid, identifying glandular enlargement, its characteristics, and the presence of nodules. Confirmation requires TSH measurement, which should be normal, ruling out hormonal dysfunction. Cervical ultrasonography documents glandular volume, characterizes morphology (diffuse, uninodular, or multinodular), and identifies nodule characteristics when present. In selected cases, thyroid scintigraphy and fine-needle aspiration biopsy complement the investigation, especially to evaluate nodules and exclude malignancy.

Is treatment available in public health systems?

Yes, treatment of nontoxic goiter is generally available in public health systems, although the approach varies according to severity. Mild cases without symptoms may require only periodic clinical follow-up, which is universally accessible. Pharmacological treatments, when indicated, include suppressive levothyroxine or radioiodine, typically available in public services. Surgery (thyroidectomy) is reserved for cases with compressive symptoms, progressive growth, suspicion of malignancy, or significant aesthetic reasons, and is generally offered in referral centers within public health systems.

How long does treatment last?

Treatment duration varies widely depending on the chosen approach. Patients under clinical observation without active intervention may be followed indefinitely with periodic annual or biannual evaluations. When suppressive treatment with levothyroxine is chosen, the typical duration is 12 to 24 months, with subsequent reassessment. Radioiodine treatment is generally a single intervention, although it may require additional doses if the response is insufficient. Surgery is definitive, but post-operative follow-up is necessary, especially if total thyroidectomy is performed, requiring lifelong hormone replacement.

Can this code be used in medical certificates?

Yes, code 5A01 can and should be used in medical certificates when appropriate. However, it is important to consider the context. For temporary absences related to diagnostic procedures (such as biopsy or scintigraphy) or therapeutic procedures (surgery or radioiodine), the code adequately documents the condition. For prolonged absences, it may be necessary to detail complications or specific symptoms. In documents for social security or benefits purposes, precise coding is essential for adequate case analysis.

Can nontoxic goiter progress to cancer?

Although most nontoxic goiters are benign, thyroid nodules, even in multinodular goiters, may eventually harbor malignancy. The risk of cancer in multinodular goiter is generally low but not negligible. Therefore, adequate ultrasonographic evaluation and fine-needle aspiration of nodules with suspicious characteristics are fundamental. Periodic follow-up allows early detection of changes that may suggest malignant transformation, although it is important to emphasize that nontoxic goiter itself is not considered a pre-malignant lesion.

Is treatment necessary in all cases?

No. Many patients with nontoxic goiter, especially when of small volume, asymptomatic, and without progressive growth, can be followed clinically without active intervention. The therapeutic decision considers multiple factors: glandular volume, presence of compressive symptoms, documented growth, nodule characteristics, risk of malignancy, aesthetic impact, and patient preferences. Voluminous, symptomatic goiters, or those with suspicious nodules generally require intervention, while discrete and stable enlargements may be merely observed.

What is the difference between goiter and thyroid nodule?

Goiter refers to general enlargement of the thyroid gland, which may be diffuse (homogeneous) or nodular (with nodular formations). Thyroid nodule is a focal lesion within the gland, which may exist in isolation without significant glandular enlargement or as part of a multinodular goiter. A patient may have a nodule without goiter (normal-sized thyroid with focal nodule) or goiter without nodules (homogeneous diffuse enlargement). Code 5A01 encompasses both diffuse and nodular goiters, provided there is no hormonal dysfunction.

Does iodine deficiency always cause goiter?

Iodine deficiency is an important cause of goiter in endemic regions, but not all exposed individuals develop glandular enlargement. Individual response varies according to genetic factors, severity and duration of deficiency, and presence of other goitrogens. Furthermore, nontoxic goiter can occur in areas without iodine deficiency, due to sporadic causes, genetic factors, or other environmental factors. Salt iodization programs have significantly reduced the prevalence of endemic goiter in many regions, but have not completely eliminated cases of nontoxic goiter.

Conclusion:

The ICD-11 code 5A01 for nontoxic goiter represents an essential tool in the accurate documentation of a prevalent thyroid condition. Clear understanding of diagnostic criteria, appropriate use situations, important exclusions, and differentiation of related conditions ensures adequate coding, with positive impacts on the quality of health records, clinical management, and epidemiological research. The transition from ICD-10 to ICD-11 offers opportunities for greater specificity and logical organization, benefiting healthcare professionals and information systems globally.

External References

This article was prepared based on reliable scientific sources:

References verified on 2026-02-03

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