Subacute De Quervain thyroiditis is a form of self-limiting inflammatory thyroiditis characterized by anterior neck pain, elevated inflammatory markers, and a typical multiphasic functional course: an initial phase of thyrotoxicosis caused by the release of preformed hormones, often followed by a phase of transient hypothyroidism and, in most cases, recovery of thyroid function. The process is classically considered “post-viral” or virus-related, but the central pathogenetic event is not increased hormone production. Instead, it is a destructive thyroiditis involving follicular disruption and the release of colloid-stored T4 and T3 into the circulation.
From a practical standpoint, the condition is relevant for two reasons. First, it is the most common cause of painful thyroiditis and may mimic deep neck infections or odontogenic disorders. Second, it requires accurate evaluation because the thyrotoxicosis does not benefit from antithyroid medications, and treatment is directed toward controlling pain, inflammation, and adrenergic symptoms.
Subacute thyroiditis is generally considered an uncommon condition in the general population, but it is a recognizable clinical entity because it combines thyroid pain, a marked systemic inflammatory response, and transient thyroid dysfunction. The most consistent epidemiological findings are its predominance in women and its greater frequency during adulthood, with a typical peak in middle age. Although these features are not diagnostic, they increase the pre-test probability when the clinical presentation is compatible.
Seasonality and the temporal association with upper respiratory tract infections have historically supported the hypothesis of a viral trigger. In clinical practice, many patients report an influenza-like illness in the weeks preceding the onset of neck pain, with low-grade fever, myalgia, and general malaise. A direct causal relationship with a single infectious agent is not consistently demonstrable, however, and the most widely accepted interpretation is that of post-infectious thyroid inflammation developing in a predisposed individual.
Immunogenetic background is a key component of this predisposition. Classical and subsequent studies have demonstrated an association with human leukocyte antigen (HLA) alleles, particularly HLA-B*35, while additional associated alleles have more recently been proposed in certain populations. HLA testing is not routinely included in the diagnostic pathway, but it has conceptual relevance because it suggests that the inflammatory event depends not only on infectious exposure, but also on the interaction between the trigger and immune susceptibility, which may influence clinical presentation and recurrence risk.
In recent years, the perceived epidemiology has been influenced by increased attention to thyroiditis associated with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), both after infection and after vaccination. In this setting, a balanced clinical interpretation is essential. The syndrome remains defined by pain, inflammation, and compatible laboratory and imaging patterns, while temporal proximity to an infectious event or vaccination alone cannot replace the diagnostic evaluation. The practical implication is that increased clinical awareness may reduce diagnostic delays and limit inappropriate antibiotic use in patients who have neck pain and low-grade fever but actually have subacute thyroiditis.
Factors that may influence presentation include the magnitude of the systemic inflammatory response, the individual pain threshold, and the presence of cardiac or anxiety-related comorbidities that make the adrenergic symptoms of thyrotoxicosis more evident. Another clinically relevant epidemiological feature is that some patients may experience recurrence, often after overly rapid reduction of anti-inflammatory treatment or in individuals with immunogenetic susceptibility. The therapeutic approach must therefore balance rapid symptom control with an adequate tapering duration when glucocorticoids are used.
Subacute De Quervain thyroiditis is traditionally described as a “post-viral” thyroiditis, but its pathophysiological core is better understood as a granulomatous inflammatory reaction that damages thyroid follicles and disrupts the barrier that normally separates the colloid from the vascular compartment. Under physiological conditions, the thyroid stores large quantities of iodinated thyroglobulin within the follicular lumen. When follicular architecture is disrupted, hormones and precursors are released in large amounts into the bloodstream, causing thyrotoxicosis not through increased synthesis, but through the leakage of preformed contents.
This distinction explains several clinical and diagnostic findings. Because de novo synthesis is reduced during the destructive phase, thyroid iodine uptake is typically low, and antithyroid medications do not alter the clinical course. Initial thyrotoxicosis is instead associated with signs of tissue release, such as increased thyroglobulin, and with a marked systemic inflammatory response, including elevated erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP), which represent distinguishing features compared with other forms of thyrotoxicosis.
Histopathologically, the term “granulomatous” reflects inflammation involving giant cells and follicular disruption, with an initial phase of tissue injury and removal of colloidal material followed by remodeling and healing. The characteristic pain results from the combination of edema, capsular tension, involvement of perithyroidal structures, and local inflammatory mediators. Tenderness on palpation and radiation toward the jaw or ear are manifestations of this regional neuroinflammatory component.
The multiphasic course is the direct consequence of the kinetics of tissue injury and regenerative capacity. During the first phase, excess circulating T4 and T3 suppress thyroid-stimulating hormone (TSH) and produce adrenergic symptoms. When colloidal stores are depleted and inflammation reduces synthetic capacity, the patient may enter a phase of transient hypothyroidism, during which TSH rises and free thyroxine (FT4) may decrease. As inflammation resolves and the follicular epithelium is restored, thyroid function tends to normalize. In a minority of cases, residual damage results in persistent hypothyroidism requiring replacement therapy.
The HLA predisposition suggests that the pathogenesis involves antigen presentation mechanisms and cell-mediated immune responses. Within this framework, an infectious trigger may initiate the process through molecular mimicry or amplification of the inflammatory response, involving a complex interaction among innate immunity, cytokines, and cellular recruitment. Clinically, this results in heterogeneous presentations. Some patients have a predominantly painful and inflammatory syndrome, others mainly exhibit systemic manifestations and thyrotoxicosis, and in some cases recurrence may reflect persistent immune activation or incomplete resolution of the inflammatory phase.
A final pathophysiological consideration concerns the systemic impact of transient thyrotoxicosis. Even though its duration is limited, excess thyroid hormone may be clinically significant in patients with heart disease, arrhythmic susceptibility, or frailty because it increases heart rate, contractility, and myocardial oxygen consumption. In these patients, careful assessment of adrenergic symptoms and timely symptomatic treatment with beta-blockers become integral components of management, regardless of the intensity of local pain.
The typical clinical presentation combines painful local symptoms with a systemic inflammatory syndrome, often accompanied by signs of thyrotoxicosis. The onset may be preceded by an influenza-like prodromal phase, followed by anterior neck pain described as deep, throbbing, or stabbing, often aggravated by swallowing, neck rotation, or palpation. A characteristic feature is radiation of the pain toward the jaw, ear, or occipital region, which may lead to dental or otolaryngological consultations before an endocrine diagnosis is considered.
During history taking, low-grade fever or fever, myalgia, marked fatigue, and general malaise are frequently reported in addition to pain. Functional thyroid involvement may cause palpitations, heat intolerance, sweating, fine tremor, irritability, and insomnia, with variable intensity. In some cases, tachycardia is perceived as the predominant symptom, particularly in anxious patients or those with pre-existing cardiovascular disease, while neck pain may be minimized or attributed to pharyngitis.
On physical examination, the thyroid may be heterogeneously enlarged and, most importantly, tender on palpation. Tenderness may be focal or migrate between the two lobes, and the gland may feel firm because of edema and inflammation. The overlying skin generally does not show the typical signs of cellulitis, which is useful in the differential diagnosis with deep bacterial infections, although mild local erythema may be present. Systemic signs of thyrotoxicosis, such as sinus tachycardia, tremor, and hyperreflexia, may coexist without the typical findings of Graves disease, such as orbitopathy or a hypervascular goiter with a palpable thrill.
The clinical course evolves over time. During the initial phase, painful and inflammatory symptoms may be severe and disabling, with reduced food intake because of odynophagia and disturbed sleep. With anti-inflammatory treatment and the natural resolution of the process, pain tends to decrease, while thyrotoxicosis may persist for several weeks as hormone stores are depleted. Subsequently, some patients report a different type of fatigue, weight gain, cold intolerance, or psychomotor slowing, compatible with the phase of transient hypothyroidism. This phase must be actively recognized to prevent its symptoms from being attributed to nonspecific convalescence.
Several atypical presentations may complicate the diagnostic pathway. In some cases, the disorder may mimic a thyroid nodule or mass, or it may present predominantly with fever and elevated inflammatory markers without clearly reported pain, particularly when the patient has already taken analgesics. Migration of pain between the lobes and variability in adrenergic symptoms explain why clinical assessment must always integrate the temporal history, physical examination, and biochemical findings.
Subacute thyroiditis should be suspected in a patient with anterior neck pain and thyroid tenderness associated with systemic signs of inflammation. The presentation is particularly suggestive when the pain radiates to the jaw or ear, when low-grade fever is present, and when symptoms began after a respiratory illness during the preceding weeks. In this setting, the most common error is to interpret the symptoms as pharyngotonsillitis, otitis, or an odontogenic disorder, resulting in diagnostic delays and non-targeted antibiotic treatment.
Another finding that should increase clinical suspicion is the coexistence of signs of thyrotoxicosis in a painful and inflammatory setting. The combination of tachycardia, tremor, and heat intolerance with thyroid pain is more compatible with destructive thyroiditis than with autoimmune hyperthyroidism, particularly when orbitopathy and a hypervascular goiter are absent. In patients with heart disease or arrhythmic susceptibility, suspicion must arise promptly because even transient thyrotoxicosis may precipitate heart failure or arrhythmias.
The condition should also be suspected when the pain is migratory, worsens with swallowing or neck movement, and physical examination reveals a tender goiter or asymmetric thyroid swelling. The variability of presentation requires a pragmatic approach. Suspicion arises from the integration of pain location, inflammatory signs, and possible thyroid dysfunction, rather than from the presence of a single pathognomonic finding.
In recent clinical contexts, the onset of compatible symptoms after SARS-CoV-2 infection or vaccination may be recorded as a temporal factor in the medical history. Suspicion should not be automatic in these cases, but the presence of thyroid pain, elevated inflammatory markers, and a consistent laboratory pattern justifies early investigation. The clinical objective is to identify promptly those patients who require more intensive pain control or closer monitoring because of the cardiovascular effects of thyrotoxicosis.
Finally, suspicion should remain high when a patient with neck pain and low-grade fever does not respond to empirical treatment for ear, nose, and throat infections and develops worsening quality of life, insomnia, and palpitations. In this setting, thyroid assessment becomes essential to avoid unnecessary diagnostic pathways and to establish treatment consistent with the destructive pathogenetic mechanism.
The diagnosis of subacute thyroiditis is clinical and biochemical and is based on a sequential approach that confirms the combination of painful thyroid inflammation and destructive thyroid dysfunction, while distinguishing the condition from autoimmune hyperthyroidism, suppurative thyroiditis, and other causes of neck pain. Initial evaluation includes a targeted medical history, physical examination of the neck, and thyroid function testing with TSH, FT4, and FT3, together with inflammatory markers such as CRP and ESR. During the initial phase, the typical profile consists of suppressed TSH with elevated FT4, often with FT3 proportionally less elevated than in Graves disease, and a marked increase in CRP or ESR, consistent with systemic inflammation.
The selective use of thyroid autoantibodies is an important step. Measurement of TSH receptor antibodies and thyroid peroxidase antibodies is not used to establish the diagnosis of subacute thyroiditis, but it is useful in the differential diagnosis. Positive TSH receptor antibodies support Graves disease, whereas they are typically absent in subacute thyroiditis. Thyroid peroxidase antibodies may be present as a nonspecific finding or because of coexisting thyroid autoimmunity and should be interpreted without overestimating their importance relative to the painful and inflammatory presentation.
The first-line imaging investigation is thyroid ultrasonography, which, when performed by an experienced operator, shows hypoechoic and heterogeneous areas that may be multifocal and often have poorly defined margins. Color Doppler provides relevant differential information. During the acute phase of subacute thyroiditis, vascularity in the affected areas is typically reduced or not increased, unlike Graves disease, in which diffuse hypervascularity is observed. Ultrasonography is also useful for excluding abscesses, fluid collections, and suspicious nodular lesions requiring a different diagnostic pathway.
When uncertainty persists regarding hyperthyroidism caused by increased synthesis, the decisive functional investigation is thyroid radioactive iodine uptake or scintigraphy. In subacute thyroiditis, this generally shows low uptake, consistent with reduced iodine organification during follicular injury. When integrated with elevated inflammatory markers and pain, this finding reinforces the pathophysiological interpretation of thyrotoxicosis caused by hormone release rather than overproduction.
In the differential diagnosis with suppurative thyroiditis, pain and fever may overlap clinically. Suppurative thyroiditis, however, tends to cause more pronounced infectious manifestations, sometimes with marked leukocytosis, possible fluctuation or fluid collection on imaging, and a potentially complicated course requiring antibiotics and sometimes drainage. Therefore, in the presence of persistent high fever, rapid deterioration, immunosuppression, or suggestive ultrasonographic findings, the diagnostic workup should include blood cultures, otolaryngological evaluation, and, when indicated, ultrasound-guided aspiration for microbiological analysis.
Thyroid fine-needle aspiration is not routinely required in typical subacute thyroiditis, but it may be indicated when ultrasonography identifies a mass-like lesion, when the course is atypical, or when neoplasia or infection must be excluded. In such cases, cytology may show features compatible with granulomatous thyroiditis and help establish the diagnosis in non-classical presentations.
Finally, diagnosis must include an assessment of the expected functional evolution. After the thyrotoxic phase, gradual normalization is expected, sometimes followed by a hypothyroid phase. The diagnostic pathway therefore does not end with the initial evaluation, but requires a plan for laboratory monitoring to identify the transition between phases and to initiate temporary replacement therapy when symptoms and FT4 levels make it necessary.
Subacute De Quervain thyroiditis is defined by its painful and granulomatous pattern, but clinical classification is useful for guiding treatment and follow-up. The first classification axis concerns the functional phase: the initial thyrotoxic phase, the transitional euthyroid phase, the hypothyroid phase, and recovery. This sequence is not mandatory in every patient because some experience only a minimal or asymptomatic hypothyroid phase, whereas others develop more pronounced and prolonged hypothyroidism.
A second axis concerns the extent and intensity of thyroid involvement. Some patients have focal disease with localized pain and only modest elevation of inflammatory markers, whereas others have more extensive involvement with severe pain, fever, and marked functional impairment. Practical severity is determined not only by the intensity of thyrotoxicosis, which is often moderate, but also by the combination of pain, systemic inflammatory response, and the cardiovascular effects of the thyrotoxic phase in predisposed patients.
A third clinical dimension concerns the risk of recurrence. Recurrence may present as renewed pain and increased inflammatory markers after initial improvement, sometimes in association with overly rapid reduction of corticosteroid therapy. In such cases, it is useful to distinguish an inflammatory exacerbation from the physiological transition toward the hypothyroid phase, which may cause new symptoms but does not typically reproduce severe pain and elevated CRP.
Finally, a pragmatic classification can be based on the clinical context and may include forms temporally associated with specific viral infections or SARS-CoV-2. In such cases, the clinical syndrome remains comparable, but awareness of the context may influence the promptness of suspicion and the quality of the differential evaluation. In all subtypes, the common feature is the destructive and self-limiting nature of the process, which directs treatment toward symptom control and monitoring rather than toward therapies that inhibit thyroid hormone synthesis.
Treatment of subacute De Quervain thyroiditis is directed toward three objectives: control of pain, reduction of systemic inflammation, and management of symptoms during the thyrotoxic phase. Because excess thyroid hormone results from release rather than increased synthesis, antithyroid medications are not indicated. Treatment should instead be proportionate to clinical severity, using a stepwise approach while considering the risk of recurrence.
In mild or moderate cases, first-line treatment consists of nonsteroidal anti-inflammatory medications at anti-inflammatory doses, which can reduce pain and inflammation in a substantial proportion of patients. Clinical response during the first 24 to 72 hours is a useful practical parameter. Clear improvement supports continuation of anti-inflammatory treatment and planning of dose reduction according to symptoms and inflammatory markers. In patients with contraindications to nonsteroidal anti-inflammatory medications or with gastrointestinal or renal comorbidities, treatment must be individualized and accompanied by protective measures when appropriate.
In patients with severe pain, persistent fever, or substantial functional impairment, treatment with glucocorticoids is often the most effective option for achieving rapid symptom control. In clinical practice, prednisone or prednisolone is used at moderate initial doses, followed by gradual dose reduction guided by symptoms and CRP. The critical factor is not only the initial dose, but also the duration of tapering, because overly rapid dose reductions may promote inflammatory exacerbations. Even when pain resolves quickly, tapering should remain consistent with the physiological time required for inflammation to subside and should be accompanied by clinical monitoring.
Management of thyrotoxicosis is symptomatic. Beta-blockers are indicated when tachycardia, tremor, or anxiety is clinically significant, particularly in patients with heart disease, older age, or arrhythmic vulnerability. Selection and titration of the beta-blocker should take blood pressure, bronchospasm, and concomitant treatment into account. Control of adrenergic symptoms generally improves quality of life substantially, even though it does not alter the duration of thyrotoxicosis.
During the hypothyroid phase, some patients develop symptoms and a significant reduction in FT4. In these cases, temporary replacement treatment with levothyroxine may be appropriate, particularly when hypothyroidism is symptomatic or prolonged. The decision must remain dynamic. The objective is to treat a temporary deficiency without establishing unnecessary permanent replacement. Planned reassessment allows levothyroxine to be discontinued when thyroid function recovers, avoiding the incorrect classification of a physiological phase of the disease as persistent hypothyroidism.
Preventing therapeutic errors is an important practical consideration. Neck pain associated with low-grade fever often leads to empirical antibiotic treatment, but antibiotics provide no benefit in typical subacute thyroiditis. They should be reserved for cases in which the diagnostic evaluation supports suppurative thyroiditis or another documented infection. Similarly, invasive procedures are not indicated when ultrasonographic findings and the clinical presentation are consistent with subacute thyroiditis and the patient responds to anti-inflammatory treatment.
Follow-up aims to confirm resolution of the inflammatory process, identify transitions between functional phases, and prevent recurrence and treatment-related complications. During the acute phase, monitoring is primarily clinical and includes pain intensity, fever, ability to eat and rest, and treatment tolerability. Trends in CRP and ESR may be useful as markers of response, particularly in patients receiving glucocorticoids, because they allow dose reduction to be aligned with the regression of inflammation.
Thyroid function should be reassessed at intervals consistent with the clinical course, often every 4 to 6 weeks during the transitional phase, with the interval adjusted according to the individual presentation. This allows documentation of the transition from thyrotoxicosis to euthyroidism and identification of the hypothyroid phase when it develops. Interpretation must take the clinical context into account. FT4 often normalizes before TSH recovers, and persistent TSH suppression may reflect a physiological delay in pituitary set-point recovery rather than ongoing thyrotoxicosis.
In patients receiving glucocorticoids, follow-up must include monitoring for adverse effects, particularly hyperglycemia, insomnia, blood pressure changes, and gastrointestinal complications. Gradual dose reduction should be planned and clearly communicated because inappropriate self-management or premature discontinuation are among the factors most commonly preceding painful recurrence. When recurrence occurs, follow-up should include reassessment of the differential diagnosis and implementation of a slower tapering schedule, avoiding repeated short courses that increase the risk of clinical fluctuations.
When levothyroxine has been initiated during the hypothyroid phase, reassessment with a possible supervised withdrawal trial after stabilization is essential to distinguish transient from permanent hypothyroidism. This phase requires balance. Discontinuing treatment too early may reproduce symptoms, whereas continuing it indefinitely may conceal recovery of thyroid function and result in an incorrect long-term diagnosis.
In patients with cardiovascular comorbidities, follow-up should include assessment of heart rate control and the possible need to continue beta-blockers temporarily. In the presence of arrhythmias or persistent cardiac symptoms, cardiological evaluation is appropriate because thyrotoxicosis, although transient, may act as a trigger in vulnerable individuals.
The prognosis of subacute De Quervain thyroiditis is favorable in most cases, with resolution of pain and recovery of thyroid function over time. The overall duration of the course varies, but its multiphasic pattern allows clinical prediction. The painful and inflammatory phase generally subsides within weeks, whereas complete biochemical normalization may take longer, particularly when a hypothyroid phase develops. Appropriate management reduces the risk of repeated healthcare visits, unnecessary investigations, and inappropriate treatment.
The most clinically relevant complication in routine practice is recurrence. Recurrence presents as renewed pain and increased inflammatory markers after initial improvement, often during or after reduction of corticosteroid treatment. This scenario requires differentiation between inflammatory exacerbation, other causes of neck pain, and a simple transition between functional phases. Optimal management aims to control symptoms with the lowest effective glucocorticoid exposure while maintaining a tapering schedule sufficiently gradual to follow the biological course of the disease.
A second complication is persistent hypothyroidism. Some patients do not fully recover thyroid function and require long-term replacement therapy with levothyroxine. The risk is higher when follicular damage is more extensive or when underlying autoimmune thyroid disease coexists. Functional follow-up must therefore not be omitted even after painful symptoms have resolved. The clinical relevance of persistent hypothyroidism is mainly related to quality of life and metabolic risk, and its consequences can be prevented through timely diagnosis and appropriate treatment.
Treatment-related complications depend primarily on the therapies used. Prolonged or excessive glucocorticoid exposure may cause metabolic and cardiovascular adverse effects. Levothyroxine continued beyond the period of actual need may cause mild iatrogenic thyrotoxicosis, with an increased arrhythmic risk in predisposed individuals. Inappropriate antibiotic use is also an indirect complication because it exposes patients to adverse effects and contributes to inefficient clinical pathways.
Rare but clinically important events include presentations that mimic thyroid masses, with the consequent risk of unnecessary invasive procedures, and cardiac complications in frail patients during the thyrotoxic phase. In these situations, accurate initial evaluation, targeted use of ultrasonography, and appropriate clinical monitoring are the factors that support a favorable outcome without overtreatment.