New aspects in the pathogenesis and management of subacute thyroiditis

Subacute thyroiditis (SAT) is a thyroid inflammatory disease, whose pathogenesis and determinants of the clinical course were unclear for many decades. The last few years have brought many clinically significant new data on the epidemiology, pathogenesis and management of SAT. Several human leukocyte antigen (HLA) alleles were demonstrated not only to increase the risk of SAT, but also to correlate with SAT clinical course and determine the risk of recurrence. The world-wide epidemic of the coronavirus disease 19 (COVID-19) has provided new observations that the severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) can be a potent SAT-triggering factor, and that the clinical course of SAT in patients affected by COVID-19 is different from a typical one. Additionally, many new trends in the clinical course are emerging. In the last years, painless course of SAT is more and more often described, constituting a special challenge in patients hospitalized due to COVID-19. Despite an excellent availability of diagnostic methods, several difficulties in SAT differential diagnosis can be currently encountered and the proper diagnosis and treatment is frequently delayed. False positive diagnoses of SAT in patients with malignancies of poor prognosis constitute a life-threatening problem. Taking into account all the new aspects of SAT pathogenesis and of its clinical course, the new - modified - SAT diagnosis criteria have been proposed.

Subacute thyroiditis as a presenting manifestation of COVID-19: a report of an exceedingly rare clinical entity

The SARS-CoV-2 has wreaked havoc globally and has claimed innumerable lives all over the world. The symptoms of this disease may range from mild influenza-like symptoms to severe acute respiratory distress syndrome with high morbidity and mortality. With improved diagnostic techniques and better disease understanding, an increased number of cases are being reported with extrapulmonary manifestations of this disease ranging from renal and gastrointestinal to cardiac, hepatic, neurological and haematological dysfunction. Subacute thyroiditis is a self-limiting and painful thyroid gland inflammation most often secondary to viral infections. We report a case of subacute thyroiditis in a 58-year-old gentleman presenting with a painful swelling in the neck who was subsequently detected to be positive for SARS-CoV-2. We seek to highlight the broad clinical spectrum of the COVID-19 by reporting probably the first case of subacute thyroiditis possibly induced by SARS-CoV-2 infection from India.

[Non-autoimmune thyroiditis]

The term thyroiditis comprises a group of thyroid diseases characterized by the presence of inflammation, including autoimmune and non-autoimmune entities. It may manifest as an acute illness with severe thyroid pain (subacute thyroiditis and infectious thyroiditis), and conditions in which the inflammation is not clinically evident evolving without pain and presenting primarily thyroid dysfunction and/or goiter (drug-induced thyroiditis and Riedel thyroiditis). The aim of this review is to provide an updated approach on non-autoimmune thyroiditis and its clinical, diagnostic and therapeutic aspects.

An unusual clinical presentation of subacute granulomatous thyroiditis

Subacute granulomatous thyroiditis is an inflammatory thyroid condition that is presumed to be caused by a viral infection or postviral inflammatory process. It is characterized by neck pain, usually a tender diffuse goiter, and thyrotoxicosis. A case is presented of subacute granulomatous thyroiditis in an adult woman who had no neck pain but presented with morning stiffness in the small joints of the right hand, intermittent abdominal pain, malaise, fever, and myalgia. After the diagnosis had been established, she was treated with propranolol and acetylsalicylic acid, and has fully recovered. In conclusion, this disease may be difficult to diagnose, especially if there is a combination of fever and increased aminotransferases, which can lead to a wrong diagnostic approach.

Subacute thyroiditis presenting as acute psychosis: a case report and literature review

We describe herein an unusual case of subacute thyroiditis presenting as acute psychosis. An 18-year-old male presented at the emergency department due to abnormal behavior, psychomotor agitation, sexual hyperactivity, and a paranoid mental state. Laboratory findings included an erythrocyte sedimentation rate of 36 mm/hr (normal range, 0 to 9), free T4 of 100.0 pmol/L (normal range, 11.5 to 22.7), and thyroid stimulating hormone of 0.018 mU/L (normal range, 0.35 to 5.5). A technetium-99m pertechnetate scan revealed homogeneously reduced activity in the thyroid gland. These results were compatible with subacute thyroiditis, and symptomatic conservative management was initiated. The patient's behavioral abnormalities and painful neck swelling gradually resolved and his thyroid function steadily recovered. Although a primary psychotic disorder should be strongly considered in the differential diagnosis, patients with an abrupt and unusual onset of psychotic symptoms should be screened for thyroid abnormalities. Furthermore, transient thyroiditis should be considered a possible underlying etiology, along with primary hyperthyroidism.

Subacute, silent, and postpartum thyroiditis

Subacute, silent, and postpartum thyroiditis are temporary forms of thyroid dysfunction caused by thyroid gland inflammation. They classically present with a triphasic course: a brief period of thyrotoxicosis due to release of preformed thyroid hormone that lasts for 1 to 3 months, followed by a more prolonged hypothyroid phase lasting up to 6 months, and eventual return to a euthyroid state. However, the types and degree of thyroid dysfunction are variable in these disorders, and individual patients may present with mild or more severe cases of thyrotoxicosis alone, hypothyroidism alone, or both types of thyroid dysfunction.

Simultaneous occurrence of subacute thyroiditis and Graves' disease

BACKGROUND

Rare cases of Graves' disease occurring years after subacute thyroiditis (SAT) have been reported. Here, we present the first known case of simultaneous occurrence of Graves' disease and SAT.

PATIENT FINDINGS

A 41-year-old woman presented with 10 days of neck pain, dysphagia, and hyperthyroid symptoms. Neck pain had initially started at the base of the right anterior neck and gradually spread to her upper chest, the left side of her neck, and bilateral ears. Physical examination revealed a heart rate of 110 beats/minute and a diffusely enlarged tender thyroid gland without evidence of orbitopathy. There was a resting tremor of the fingers and brisk deep tendon reflexes. Laboratory values: thyrotropin<0.01 mcIU/mL (nL 0.39-5.33), free thyroxine 2.0 ng/dL (nL 0.59-1.60), free T3 6.6 pg/mL (nL 2.3-4.2), thyroglobulin 20.1 ng/mL (nL 2.0-35.0), thyroglobulin antibody 843 IU/mL (nL 0-80), thyroperoxidase antibody 130 IU/mL (nL 0-29), thyroid stimulating hormone receptor antibody 22.90 IU/L (nL<1.22), thyroid stimulating immunoglobulins 299 units (nL<140), erythrocyte sedimentation rate 120 mm/h (nL 0-20), and C-reactive protein 1.117 mg/dL (nL 0-0.5). Human leukocyte antigen (HLA) typing revealed DRB1, DR8, B35, B39, DQB1, DQ4, and DQ5. A thyroid ultrasound showed an enlarged heterogeneous gland with mild hypervascularity. Fine-needle aspiration (FNA) biopsies of both thyroid lobes revealed granulomatous thyroiditis. The thyroid scan showed a diffusely enlarged gland and heterogeneous trapping. There was a focal area of relatively increased radiotracer accumulation in the right upper pole. The 5-hour uptake ((123)I) was 6.6% (nL 4-15). The patient was symptomatically treated. Over the next several weeks, she developed hypothyroidism requiring levothyroxine treatment.

SUMMARY

This case illustrates a rare simultaneous occurrence of Graves' disease and SAT. Previous case studies have shown that Graves' disease may develop months to years after an episode of SAT. A strong family history of autoimmune thyroid disorders was noted in this patient. Genetic predilection was also shown by HLA typing.

CONCLUSION

Although the occurrence of SAT with Graves' disease may be coincidental, SAT-induced autoimmune alteration may promote the development of Graves' disease in susceptible patients. Genetically mediated mechanisms, as seen in this patient by HLA typing and a strong family history, may also be involved.

Association of the ultrasonographic findings of subacute thyroiditis with thyroid pain and laboratory findings

We aimed to determine whether ultrasonography is a useful diagnostic tool by correlating its findings with biological data of patients with subacute thyroiditis (SAT). Thirty-two SAT patients were evaluated in a retrospective study. Thirty-one patients (96.9%) had tenderness, 14 (43.8%) had localized pain, and 11 patients (34.4%) had radiating pain during a state of SAT. With ultrasonography, we found 51 hypoechoic areas in 32 patients. The hypoechoic volume per unilateral thyroid gland (%) was significantly larger in areas accompanied with pain (P<0.001). Out of 27 patients measured, 18 (67%) were positive for thyroglobulin antibodies (TgAb), of whom all were females. TgAb levels ranged from 0.3 to 13.8 U/ml. During therapy, TgAb levels gradually increased in 2 of the 7 patients who were measured several times. Both thyroglobulin antigen (TgAg) and free thyroxine (FT4) correlated well with total hypoechoic volume (cm (3) ), and the TgAg level showed a strong correlation with the FT4 level (r = 0.7; P<0.0001). The area (%) that the hypoechoic volume occupied in the total thyroid gland, even if the area was over half, was not related to the need of L-T4 replacement therapy. Also, none of the other variables (age, days from onset until diagnosis, serum levels of FT4, TgAg, CRP, autoantibodies, therapies, treatment) differed between the patients with and without replacement therapy. In summary, we found that the hypoechoic area in patients with SAT reflected the degree of inflammation and thyroid hormone levels, though it was difficult to predict continuous hypothyroidism.

Demographic and clinical features of patients with subacute thyroiditis: results of 169 patients from a single university center in Turkey

BACKGROUND

Turkey is an endemic area for thyroid diseases. The Aegean region is well documented for increased prevalence of thyroid disorders. In this study we investigated the demographic and clinical features of subacute thyroiditis (SAT) patients who had been diagnosed and treated in Ege University.

METHODS

The hospital files of patients admitted to the endocrinology clinic of Ege University between January 1987 and December 2001 were retrospectively evaluated. Patients who had been diagnosed as having any thyroid disorder were determined.

RESULTS

176 fulfilled diagnostic criteria for SAT. The majority of patients with SAT were diagnosed as having subacute granulomatous thyroiditis (169/176) (134 females, 35 males, mean age 34.0+/-17.8 yr); 69% of the patients were between 30-50 yr of age. Thyroid pain was present in 97.1% of female patients, and in 100% of male patients. High fever was evident in 78 patients (46.2%). Mean erythrocyte sedimentation rate (ESR) was 43.42+/-39.68 mm/h. Anti-thyroglobulin antibody was positive in 20%, and anti-thyroid peroxydase antibody was positive in 4% of patients. Among patients who were treated with non-steroidal anti-inflammatory drugs (NSAD) 10 female patients (10.6%), and 3 male patients (12%) developed recurrence of the disease. Among patients who were treated with prednisolone 7 female patients (17.5%), and one male patient (10%) developed recurrence. There was no significant difference regarding the recurrence rates between patients who were treated with NSAD and patients who were treated with prednisolone.

CONCLUSION

With the exception of ESR, demographic, clinical, laboratory, and imaging findings and prognoses of our patients were comparable to the previous reports.

Incessant ventricular tachycardia due to subacute thyroiditis

Subacute thyroiditis is a possibly viral, inflammatory thyroid disorder which can cause thyrotoxicosis. Ventricular arrhythmias are uncommon in thyrotoxicosis and usually occur only in those with marked heart failure or associated cardiac disease. In this case, we present a 52-year-old woman having incessant ventricular tachycardia due to subacute thyroiditis without underlying cardiac disease.

A rare case of subacute thyroiditis causing thyroid storm

Thyroid storm is a rare but potentially fatal condition that is most frequently associated with Graves' disease. We present the case of a young woman who presented in thyroid storm, later diagnosed as being due to severe subacute thyroiditis. We discuss the diagnostic approach to thyroid storm, the initial management, and eventual treatment and course of subacute thyroiditis. This case illustrates the necessity to include subacute thyroiditis in the differential diagnosis of severe thyrotoxicosis and thyroid storm.

Decreasing TNF-alpha results in less fibrosis and earlier resolution of granulomatous experimental autoimmune thyroiditis

Granulomatous experimental autoimmune thyroiditis (G-EAT) is induced in DBA/1 mice by adoptive transfer of mouse thyroglobulin (MTg)-primed spleen cells. TNF-alpha is an important proinflammatory cytokine and apoptotic molecule involved in many autoimmune diseases. To study its role in G-EAT, anti-TNF-alpha mAb was given to recipient mice. Disease severity was comparable between mice with or without anti-TNF-alpha treatment at days 19-21, the time of maximal severity of G-EAT, suggesting TNF-alpha is not essential for development of thyroid inflammation. However, thyroid lesions resolved at day 48 in anti-TNF-alpha-treated mice, while thyroids of rat Ig-treated controls had fibrosis. These results suggested that reducing TNF-alpha contributed to resolution of inflammation and inhibited fibrosis. Gene and protein expression of inflammatory molecules was examined by RT-PCR and immunostaining, and apoptosis was detected using TUNEL staining and an apoptosis kit. Thyroids of anti-TNF-alpha-treated controls had reduced proinflammatory and profibrotic molecules, e.g., IFN-gamma, IL-1beta, IL-17, inducible NOS and MCP-1, at day 19 compared with thyroids of rat Ig-treated mice. There were more apoptotic thyrocytes in rat Ig-treated controls than in anti-TNF-alpha-treated mice. The site of expression of the anti-apoptotic molecule FLIP also differed between rat Ig-treated and anti-TNF-alpha-treated mice. FLIP was predominantly expressed by inflammatory cells of rat Ig-treated mice and by thyrocytes of anti-TNF-alpha-treated mice. These results suggest that anti-TNF-alpha may regulate expression of proinflammatory cytokines and apoptosis in thyroids, resulting in less inflammation, earlier resolution, and reduced fibrosis.

Long-term outcome of thyroid function after amiodarone-induced thyrotoxicosis, as compared to subacute thyroiditis

BACKGROUND

Two main forms of amiodarone- induced thyrotoxicosis (AIT) exist: type 1 AIT is a condition of true hyperthyroidism developing in patients with pre-existing thyroid disorders, and usually requires thyroid ablative treatment. On the other hand, type 2 AIT is a form of destructive thyroiditis occurring in normal thyroids, the management of which usually consists in glucocorticoid treatment.

AIM

To assess the long-term outcome of thyroid function in a prospective study of type 2 AIT patients, as compared to patients with De Quervain's subacute thyroiditis (SAT).

PATIENTS AND METHODS

Sixty consecutive patients with type 2 AIT were evaluated during oral glucocorticoid treatment (oral prednisone 30 mg/day, gradually tapered and withdrawn over a 3-month period) and followed for 38+/-4 months (range 6-72) thereafter. Sixty consecutive patients with SAT, referred to our Institutes during the same period and treated with the same therapeutic schedule, served as controls.

RESULTS

Type 2 AIT patients were older (p<0.0001) and showed a larger male preponderance (M:F 3.6:1 vs 0.5:1, p<0.0001) than SAT patients. Mean serum free T4 (FT4) and free T3 (FT3) concentrations at diagnosis were increased in both conditions, but higher in type 2 AIT than in SAT (FT4 47.6+/-18.8 and 29.6+/-8.3 pmol/l, respectively, p<0.0001; FT3 15.4+/-7.0 and 11.2+/-3.0 pmol/l, respectively, p<0.001). Correction of thyrotoxicosis was obtained in all patients in both groups, but restoration of euthyroidism occurred earlier in SAT than in type 2 AIT (p=0.006). Ten type 2 AIT patients (17%) and 3 SAT patients (5%, p<0.03) became permanently hypothyroid after glucocorticoid withdrawal and required levothyroxine replacement.

CONCLUSIONS

A relevant proportion of type 2 AIT patients develop permanent hypothyroidism after correction of thyrotoxicosis. Thus, periodic surveillance of thyroid status is required after type 2 AIT.

Thyroiditis: differential diagnosis and management

Thyroiditis is a group of inflammatory thyroid disorders. Patients with chronic lymphocytic thyroiditis (also referred to as Hashimoto's thyroiditis) present with hypothyroidism, goiter, or both. Measurement of serum thyroid autoantibodies and thyroglobulin confirms the diagnosis. Subacute granulomatous thyroiditis (sometimes referred to as de Quervain's disease) is a self-limited but painful disorder of the thyroid. Physical examination, elevated erythrocyte sedimentation rate, elevated thyroglobulin level and depressed radioactive iodine uptake (RAIU) confirm the diagnosis. Subacute lymphocytic thyroiditis (silent thyroiditis) is considered autoimmune in origin and commonly occurs in the postpartum period. Symptoms of hyperthyroidism and depressed RAIU predominate. Acute (suppurative) thyroiditis is a rare, infectious thyroid disorder caused by bacteria and other microbes. The rare, invasive fibrous thyroiditis (Riedel's thyroiditis) presents with a slowly enlarging anterior neck mass that is sometimes confused with a malignancy.

[A painful inflammation of the thyroid]

Four women aged 30, 29, 52 and 43 years presented with what appeared to be subacute thyroiditis (De Quervain's thyroiditis). This disease is characterized by fatigue, a painful thyroid gland and thyrotoxic manifestations. The diagnosis is further based on a high erythrocyte sedimentation rate and low tracer uptake during thyroid scintigraphy. Only the first patient showed a typical course. In the second and third ones the painful thyroid was associated with nodular enlargement. Fine needle aspiration cytology was at first consistent with subacute thyroiditis but a repeated aspiration showed papillary carcinoma in the second and anaplastic carcinoma in the third patient. In the fourth one, subacute thyroiditis was accompanied by normochromic anaemia, a low serum albumin concentration and liver function disorders. She made a full recovery without treatment. Thyroid malignancies can mimic subacute thyroiditis. Persistent nodular enlargement of the thyroid is suspicious and requires careful investigation.

Syndromes of thyrotoxicosis with low radioactive iodine uptake

It is very important to diagnose correctly the etiology of thyrotoxicosis, because the course and treatment of thyrotoxicosis with low radioactive iodine uptake differ significantly from that of hyperthyroidism due to Graves' disease or toxic nodular goiter. Many causes of subacute thyroiditis have been identified producing a characteristic course of transient hyperthyroidism, followed by hypothyroidism, and usually recovery. Ectopic hyperthyroidism includes factitious thyroid hormone ingestion, struma ovarii, and, rarely, large deposits of functioning thyroid cancer metastases. Iodine-induced hyperthyroidism may be associated with low radioiodine uptakes. Amiodarone-associated hyperthyroidism may be the result of subacute thyroiditis or iodine-induced hyperthyroidism; assessment and treatment can be quite challenging.

The value of ultrasonography in the diagnosis and follow-up of subacute thyroiditis

Twenty-three consecutive patients with clinical and biochemical suspicion of subacute thyroiditis (SAT) were evaluated by ultrasonic scanning of the thyroid. Ultrasonic findings supported the diagnosis in all cases. In the 16 patients in whom thyroid scintigraphy was performed this was compatible with SAT. Initially, median thyroid volume was 40 mL (range 20-289) and a very low echogenicity was demonstrated in all patients. The extension of hypoechogenicity exceeded 75% in the majority of patients. Thyroid volume was significantly reduced to a median of 13 mL (range 9-40) (68% reduction, p < 0.00001) at a median follow-up period of 18 months (range 6-33) and a majority of the patients (60%) had persistent morphological abnormalities. No correlation between thyroid function and the extension of hypoechogenicity initially or at end of follow-up could be demonstrated. Recurrence was noted in 8 patients (35%), two of whom were positive for anti-TPO antibodies, but the risk of recurrence could not be correlated to the extension of hypoechogenicity or initial thyroid function. Recurrence was related to the further extention of hypoechoic areas and increase in thyroid volume, as evidenced by ultrasonography in our series. None developed thyroid antibodies, and all were euthyroid at the end of the observation period. We believe that high resolution ultrasonography has a useful supporting role in the diagnosis of subacute thyroiditis. In case of doubt and differential diagnostic considerations, it facilitates guided biopsies. Additionally, it allows determination of disease activity and thyroid size.

Inflammatory thyroid disorders

Inflammatory disorders of the thyroid, including autoimmune thyroiditis, are among the most common endocrine abnormalities encountered in clinical practice. The association of pain with these disorders, however, is relatively uncommon. Despite this observation, painful thyroid disorders comprise a significant component of the spectrum of thyroid disease. A rational approach to such patients, including history, physical examination, laboratory evaluation, radionuclide or ultrasonographic imaging, and fine needle aspiration biopsy, will allow the appropriate diagnosis to be made in the vast majority of cases.

[Subacute thyroiditis and concurrent suppurative thyroiditis in one case]

We report a 41 years old man admitted with a tender goiter, fever, thyrotoxic manifestations and atrial fibrillation. Laboratory confirmed the diagnosis of subacute thyroiditis and treatment with aspirin and propranolol was started, obtaining a rapid relief of symptoms and normalization of heart rate. On the tenth day after admission, severe dysphagia, dysphonia, irritative cough and further enlargement of the neck mass developed. Fine needle aspiration of the mass and thyroid ultrasound lead to the diagnosis of a thyroidal abscess, which was surgically excised, draining 250 ml of purulent material. Cultures were positive for Staphylococcus aureus. Patient was treated during 21 with cloxacilyn and discharged with normal thyroid function. Long term follow up has been uneventful.

Henoch-Schonlein nephritis associated with subacute thyroiditis

We present a 12-year-old boy who developed subacute thyroiditis during the course of rapidly progressive glomerulonephritis due to Henoch-Schonlein purpura (HSP) proven by clinical findings and percutaneous renal needle biopsy. The thyroid gland of the patient suddenly enlarged with mild tenderness while he was on steroid and dipyridamole therapy. Thyroid hormone levels revealed T3 0.31 ng/ml (nl: 0.52-1.75 ng ml), T4 2.53 ug/dl (nl: 4.8-12.8 ug/dl), free T3 0.80 pg/ml (nl: 2.14-5.34 pg/ml), free T4 0.2 ng/dl (nl: 0.73-1.95 ng/dl) and TSH 1.02 U/ml (nl: 0.36-3.25 U/ml). Antimicrosomal antibody was negative while antithyroglobulin antibody was slightly positive (1/80+). Hypoactivity with a spotty pattern was demonstrated by thyroid scanning. Serologically proven mumps infection was detected and may have been a triggering factor in the development of both HSP and subacute thyroiditis.

Coincidence of severe aplastic anaemia with multiple sclerosis or thyroid disorders. Report of 5 cases

Five patients with severe aplastic anaemia (SAA) who, simultaneously (n = 3) or consecutively (n = 2), presented with multiple sclerosis (MS) (n = 2) or immune hyperthyroidism (IHT) (n = 2) or subacute thyroiditis (n = 1) are described. Two female patients with MS developed SAA after a small dose of azathioprine. Another patient simultaneously presented with IHT and SAA. SAA and MS responded to cyclosporine while IHT required 131I. Relapsing SAA in 1 patient with MS was treated with antithymocyte globulin (ATG) which induced acute exacerbation of MS. Despite the low total dose of ATG (31.5 mg/kg), complete remission of SAA was obtained. Two other patients developed thyroid disorders, 42 and 106 months after successful immunosuppression with ATG/high-dose methylprednisolone. IHT and subacute thyroiditis were successfully treated with 131I or prednisolone, respectively, without recurrence of SAA in both cases. These are the first documented cases of SAA evolving in the course of MS while the coincidence with IHT was already described. Since enhanced expression of interferon-gamma plays a crucial role in SAA as well as in MS and in IHT, similar pathogenetic principles may apply for these seemingly unrelated disorders.

Thyroid masses: approach to diagnosis and management in childhood and adolescence

The approach to the evaluation of a neck mass requires careful history and physical examination to determine if the mass is thyroidal or non-thyroidal. Thyromegaly can be classified as diffuse or nodular, painless or painful, or associated with a solitary or multiple nodules. While the most common cause of diffuse enlargement is chronic lymphocytic thyroiditis, the presence of nodularity should prompt consideration of cancer. Results of a radionuclide scan, ultrasonogram, and/or a fine-needle aspiration of a cystic nodule should help guide the physician to those patients in need of an open thyroid biopsy.

The management of subacute (DeQuervain's) thyroiditis

Subacute (DeQuervain's) thyroiditis is a transient inflammatory thyroid disease usually associated with pain and tenderness of the gland, as well as generalized somatic symptoms, which can cause great discomfort or even complete prostration for weeks or months if left untreated. It is almost certainly the result of a viral infection. There is no definitive therapy for painful subacute thyroiditis, but there is effective treatment that will ameliorate the symptoms and allow the disease to run its spontaneous course in an asymptomatic fashion. Salicylates and nonsteroidal antiinflammatory drugs can be used in patients with mild or moderate forms of the disorder. In more severe forms of the condition, corticosteroids in suitable pharmacological dosage will generally cause a rapid relief of symptoms within 24-48 h. Prednisone may be initiated in dosages of 40 mg daily, with a gradual reduction in dosage thereafter over several weeks. Recurrences do appear in a small percentage of patients, necessitating restoration of a higher dose once again. Repeat exacerbations are uncommon. Other less common forms of treatment include triiodothyronine or thyroxine, generally to prevent repeated exacerbations. Irradiation is no longer employed. Thyroidectomy should be considered only in that very small minority of patients who have repeated relapses despite appropriate treatment. During the period of transient hypothyroidism, thyroxine may be provided but can usually be discontinued subsequently. General recovery is almost the universal rule and only less than 1% become permanently hypothyroid.

Thyroiditis. Acute, subacute, and chronic

Inflammatory diseases of the thyroid are collectively the commonest thyroid disorder. Individually, they range from the rare case of acute bacterial thyroiditis to the other end of the spectrum, the even rarer Riedel's thyroiditis. Relatively common thyroid inflammatory diseases include the subacute thyroiditis syndromes. Of particular interest to endocrinologists is that both subacute granulomatous (painful) thyroiditis and subacute lymphocytic (painless) thyroiditis are very similar in terms of clinical course, although most likely have different etiologies. Nevertheless, their similarities suggest the possibility that there may be etiologic heterogeneity for the syndromes. From a clinical standpoint, it is essential to differentiate subacute painless thyroiditis from Graves' disease, because these two disorders also may mimic each other, yet only Graves' disease requires specific therapy. Chronic lymphocytic (Hashimoto's) thyroiditis, the commonest of the thyroiditides, presents with goiter and either hyperthyroidism (uncommon), hypothyroidism (common), or euthyroidism (most common). When L-T4 therapy is used in the treatment of Hashimoto's thyroiditis, the physician must be alert to the possibility of excess thyroid hormone administration. Sensitive TSH measurements help to avoid this therapeutic pitfall.

Histological, clinical and laboratory findings of acute exacerbation of Hashimoto's thyroiditis--comparison with those of subacute granulomatous thyroiditis

As reported previously, acute exacerbation of Hashimoto's thyroiditis shows quite unique histological findings, namely localized edematous inflammation. Similar histological characteristics and clinical manifestations were observed in 7 of 492 patients with Hashimoto's thyroiditis (A group). Their clinical and laboratory findings were compared with those of 15 cases with subacute granulomatous thyroiditis (S group). Age and sex distribution and goiters in A group were 39 +/- 21 years old (mean +/- s.d.), 7/0 (F/M), and 6/1 (diffuse/nodular), respectively. These were somewhat different from those of S group (45 +/- 9, 12/3, and 3/12, respectively). Thyroid functions in A group showed wide variation: 3 cases were euthyroid, 2 were mildly hypothyroid, and one was mildly thyrotoxic and one borderline thyrotoxic, and all of the S group patients were thyrotoxic. Their thyroid radiopertechnetate uptake, scintigraphy, duration from the onset till the first visit, and ESR and CRP values were also different from those of S group. Clinical courses and outcomes of A group were generally favorable, but one of them finally underwent a total thyroidectomy. Per os and intrathyroidal administrations of steroid were effective, but there was observed a recurrence of symptoms in 3 cases. Finally, all 6 cases were left with diffuse goiters, 4 of them remaining euthyroid, and 2 falling into hypothyroidism. The acute exacerbation of Hashimoto's thyroiditis is a rare complication, which is found to be different from subacute thyroiditis on histological, clinical and laboratory findings and is generally subtle. Steroid medication is considered to be the therapeutic choice but careful observation is necessary to avoid a recurrence.