Hashimoto's thyroiditis in children and adolescents: a retrospective study on clinical, epidemiological and laboratory properties of the disease

Narrative review of pediatric thyroiditis: Diagnosis and management

OBJECTIVE

To the best of the authors' knowledge, no current literature reviews on pediatric thyroiditis exist. Our aim is to present relevant and updated information on pediatric thyroiditis subtypes and presentations.

DATA SOURCES

A narrative review was performed using PubMed and Embase.

REVIEW METHODS

A narrative literature review was performed to find articles in two databases: PubMed and Embase that discussed the various subtypes of thyroiditis in pediatric patients. Relevant key terms included: thyroiditis, pediatric, children, clinical findings, autoimmune thyroiditis, prevalence, and etiology.

DISCUSSION

112 articles were included in this review. The subtypes and clinical presentations of pediatric thyroiditis were highlighted to demonstrate that thyroid dysfunction can have unique wide-ranging effects compared to adult populations. Recommendations on diagnostic algorithms, management, and clinical consequences of delayed treatment are discussed.

CONCLUSIONS

Thyroid hormones are incredibly vital to the development of a child. It is important to identify and prevent long-term consequences clinically by implementing early treatment through awareness of these differences in clinical practice.

Thyroiditis and COVID-19: focus on pediatric age. A narrative review

PURPOSE

In light of the growing concern over the possible link between SARS-CoV2 infection and autoimmune diseases, we conducted a review to investigate the impact of the pandemic outbreak on thyroid diseases.

METHODS

We carried out a narrative review of all pediatric cases described in the literature, mainly focusing on the possible association of COVID-19 with the incidence of autoimmune and post-infective thyroid diseases (namely Hashimoto's Thyroiditis (HT), Grave's Disease (GD) and Sub-Acute Thyroiditis (SAT)). We also felt it was necessary to provide a brief review of Non-thyroidal Illness Syndrome (NTIS) and Multisystem Inflammatory Syndrome in Children (MIS-C) because of their overlap with thyroiditis.

RESULTS

There is currently no conclusive evidence linking SARS-CoV-2 infection with an increased incidence of autoimmune thyroiditis (AT) in pediatric age. However, SAT may be a mild complication of SARS-CoV-2 infection, as is the case with other viral infections. SAT typically resolves on its own and does not require treatment. NTIS may be associated with inflammatory complications, such as MIS-C, and admission to intensive care. It may also be considered a prognostic risk factor for severe disease. The hypothesized pathogenetic mechanisms of thyroid damage in COVID-19 include direct damage due to the significant expression of angiotensin-converting enzyme 2 (ACE2) in the thyroid gland, which is a ligand for the virus, and indirect damage due to immune dysregulation, such as the overproduction of IL-6, which is thought to be part of the pathogenesis of thyroiditis.

CONCLUSION

However, due to the limited evidence available, further prospective longitudinal studies are required to clarify the relationship between COVID-19 and thyroid disease in children and adolescents, as well as to investigate any potential long-term consequences.

Attention Deficit Hyperactivity Disorder Misdiagnosis: Why Medical Evaluation Should Be a Part of ADHD Assessment

INTRODUCTION

Attention deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder that interferes with multiple aspects of daily functioning and is associated with impairments in several domains. It may affect academic, educational, vocational, social, emotional, interpersonal, and health domains, and worsen risks to health outcomes.

OBJECTIVE

To identify and discuss medical conditions that commonly present with symptoms resembling ADHD.

METHOD

This review is selective and not systematic. It is conducted through a focused literature search through PubMed, Google Scholar, and EMBASE. Search term included "ADHD misdiagnosis", "medical conditions with ADHD like symptoms", "ADHD AND medical problems".

EXCLUSION

giftedness, high IQ, and any article that does not list medical conditions. The limits applied were the following: the work must have been published in the past 20 years, be on humans, and be in the English language.

RESULTS

There are several medical conditions that can be misdiagnosed as ADHD and may show a similar presentation to ADHD, particularly with inattentive symptoms. Examples include, but are not limited to, absence seizure disorder, diabetes, thyroid dysfunction, sleep deprivation, post-concussion states, inflammatory bowel disease, iron deficiency states and anemia, and disordered breathing.

CONCLUSIONS

Our review suggests that a thorough medical evaluation should be conducted prior to the diagnosis of ADHD. Allied health professionals and psychologists who diagnose ADHD should seek medical clearance from a physician prior to making the ADHD diagnosis in order to reduce misdiagnosis rates and improve patient outcomes. ADHD diagnosis should follow guidelines and be carried out under a systematic standardized approach. A full medical evaluation should be conducted to assess for medical conditions that may look like ADHD or be associated with ADHD.

Acquired Hypothyroidism in Children

Acquired hypothyroidism is generally also referred to as juvenile hypothyroidism. Hypothyroidism is due to the deficient secretion of thyroid hormones causing metabolic and neurological sequelae at the cellular level. It can present as overt hypothyroidism wherein the thyroid hormones (T4 and T3) secretion fall and thyrotropin (TSH) rises. Acquired hypothyroidism frequently presents between 9 and 11 y of age and is rarely seen before 4 y of age. Approximately 80% of the children and adolescents are asymptomatic at the time of diagnosis. Children with moderate to severe hypothyroidism often present for evaluation of poor growth, constipation, lethargy and/or dry skin. A detailed history and examination will provide us with enough clues for diagnosing hypothyroidism. Primary hypothyroidism can be diagnosed with raised TSH with subnormal levels of T3 and T4. Titres of thyroid antibodies - Anti-thyroperoxidase (TPO) and anti-thyroglobulin (ATG) antibodies, will be high in autoimmune hypothyroidism. Subclinical hypothyroidism is diagnosed with mildly elevated or high normal levels of TSH with free T4 being in the normal range. Insufficient secretion of thyrotropin from the pituitary causes central hypothyroidism. Acquired hypothyroidism is treated by replacement with levothyroxine. Regular monitoring of thyroid profile is necessary for adjusting doses of levothyroxine. Close monitoring and individualization of levothyroxine therapy is essential for normal growth and development of the child.

COVID-19-induced autoimmune thyroiditis: Exploring molecular mechanisms

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) damages multiple organs, including the thyroid, by direct invasion and cell entry via angiotensin-converting enzyme 2 or indirectly by promoting excessive inflammation in the body. The immune system is a critical factor in antiviral immunity and disease progression. In the context of SARS-CoV-2 infection, the immune system may become overly activated, resulting in a shift from regulatory to effector responses, which may subsequently promote the development and progression of autoimmune diseases. The incidence of autoimmune thyroid diseases, such as subacute thyroiditis, Graves' disease, and Hashimoto's thyroiditis, increases in individuals with COVID-19 infection. This phenomenon may be attributed to aberrant responses of T-cell subtypes, the presence of autoantibodies, impaired regulatory cell function, and excessive production of inflammatory cytokines, namely interleukin (IL)-6, IL-1β, interferon-γ, and tumor necrosis factor-α. Therefore, insights into the immune responses involved in the development of autoimmune thyroid disease according to COVID-19 can help identify potential therapeutic approaches and guide the development of effective interventions to alleviate patients' symptoms.

A Novel Inflammatory Marker for the Diagnosis of Hashimoto's Thyroiditis: Platelet-Count-to-Lymphocyte-Count Ratio

BACKGROUND

Hashimoto's thyroiditis (HT) is a chronic autoimmune thyroiditis that causes systemic inflammation in the body, leading to hypothyroidism and an enlargement of the thyroid gland.

OBJECTIVES

This study aims to reveal whether there is a relationship between Hashimoto's thyroiditis and the platelet-count-to-lymphocyte-count ratio (PLR), which is used as a new inflammatory marker.

METHODS

In this retrospective study, we compared the PLR of the euthyroid HT group and the hypothyroid-thyrotoxic HT group to the controls. We also evaluated the values of thyroid-stimulating hormone (TSH), free T4 (fT4), C-reactive protein (CRP), aspartate transaminase (AST), alanine transaminase (ALT), white blood cell count, lymphocyte count, hemoglobin, hematocrit, and platelet count in each group.

RESULTS

The PLR of the subjects with Hashimoto's thyroiditis was found to be significantly different from the control group (p < 0.001), with the rankings as follows: hypothyroid-thyrotoxic HT 177% (72-417) > euthyroid HT 137% (69-272) > control group 103% (44-243). In addition to the increased PLR values, an increase in CRP values was also observed, revealing a strong positive correlation between the PLR and CRP in the HT patients.

CONCLUSION

In this study, we found out that the PLR was higher in the hypothyroid-thyrotoxic HT and euthyroid HT patients than in a healthy control group.

What we know about the relationship between autoimmune thyroid diseases and gut microbiota: a perspective on the role of probiotics on pediatric endocrinology

INTRODUCTION

Autoimmune diseases account for a cumulative overall prevalence of about 3-5% worldwide. Among them, autoimmune thyroid diseases (ATDs) are the most common and comprise two main entities: Hashimoto's thyroiditis (HT) and Graves-Basedow disease (GD). The pathogenesis of ATDs remains not fully elucidated, however the role of microbioma has been proposed. Gut microbiota exert an important influence on the intestinal barrier, nutrient metabolism and immune system development and functions.

EVIDENCE ACQUISITION

In this review, we describe on the main features of ATDs in pediatrics, focusing on the reciprocal influence between gut microbiota, thyroid hormone metabolism and thyroid autoimmunity and consider the role of probiotics and other microbiota-targeted therapies in thyroid diseases with a perspective on pediatric endocrinology.

EVIDENCE SYNTHESIS

Microbiome affects both endogenous and exogenous thyroid hormone metabolism and influences the absorption of minerals important to the thyroid function, which are iodine, selenium, zinc and iron. The alteration of the gut microbiota, with the consequent modifications in the barrier function and the increased gut permeability, seems involved in the development of autoimmune and chronic inflammatory diseases, including ATDs. The supplementation with probiotics showed beneficial effects on the thyroid hormone and thyroid function because this strategy could restore the intestinal eubiosis and the good strain microorganism proliferation.

CONCLUSIONS

Even though the evidence about the interaction between microbiota and ATDs in pediatric patients is limited, the promising results obtained in the adult population, and in other autoimmune disorders affecting children, highlight the need of for further research in the pediatric field.

Analysis of Thyroid Gland Problems with Shear Wave Elastography in Children with Celiac Disease

BACKGROUND

The rate of autoimmune thyroiditis in children with celiac disease (CD) is high relative to the normal population. Since the majority of these patients are also euthyroid, thyroid imaging methods are gaining significance in diagnosis and follow-up. This study examines the effectiveness of thyroid ultrasonography (US) and thyroid shear wave elastography (SWE) in diagnosing thyroid disease in children with CD.

MATERIALS AND METHODS

This cross-sectional controlled study analyzed thyroid US, SWE, serum thyroid function tests, and thyroid autoimmune antibodies of 106 CD patients and 103 control patients without CD. An Aplio 500 ultrasound device with a linear array transducer and elastography software was used for thyroid US and SWE measurement of all patients.

RESULTS

Right lobe thyroid volume, left lobe thyroid volume, total thyroid volume, thyroid mean elasticity (m/s), right lobe elasticity (kPa), left lobe elasticity (kPa), and mean thyroid elasticity (kPa) levels of the CD group were higher than those of the control group (p < 0.001). The relationships between thyroid US and thyroid mean elasticity (m/s), thyroid mean elasticity (kPa), anti-thyroid peroxidase antibody, and thyroid-stimulating hormone were positive and moderate, respectively (r = 0.612, 0.612, 0.636, and 0.565, respectively; p < 0.001).

CONCLUSION

In this study, SWE findings were compatible with laboratory findings, as they constituted a sensitive and useful method in the diagnosis and follow-up of autoimmune thyroid disease in children with CD.

The Frequency of CD4+ T Cells in Women with Hashimoto's Thyroiditis

BACKGROUND

Hashimoto's thyroiditis (HT) is the most prevalent autoimmune disease, and there is no definitive treatment available for this disease. To find the appropriate therapeutic approach, it is necessary to determine the mechanism of this disease. To achieve this purpose, the frequency of CD4⁺ T cells was evaluated in patients with HT and compared with healthy individuals.

METHODS

Twenty-six female patients with HT, aged 20 - 45 years, enrolled in this study. Based on the level of thyroglobulin antibody (anti-TG) and anti-thyroid peroxidase antibody (anti-TPO) in serum of patients with HT, they were divided into two groups. The serum level of anti-TPO was above 100 IU/mL in the group 1 (n = 13), whereas the serum levels of both anti-TPO and anti-TG were above 100 IU/mL in the group 2 (n = 13). Eleven healthy women were considered control group, or group 3. Using flow cytometry, the frequency of T helper (Th)1, Th2, Th17, T regulatory type 1 (Tr1), and LT CD4⁺IL-4⁺IL-17⁺ cells and mean fluorescent intensity (MFI) of their related cytokines were evaluated.

RESULTS

The frequency of Th2 cells in the groups 1 (anti-TPO > 100) and 2 (anti-TPO > 100 and anti-TG > 100) were more than control group. Only the difference between groups 3 (healthy control) and 2 was significant (P = 0.022). The frequency of LT CD4⁺IL-4⁺IL-17⁺ cells in the group 1 was significantly more than group 3 (P = 0.027); However, the difference between group 2 and 3 was not significant (P = 0.126). The expression of interferon-gamma (IFN-γ) in the group 2 (P = 0.001) and group 1 (P = 0.001) was significantly higher than group 3. The frequency of Th17, Th1, and Tr1 cells and MFI of IL-17 and IL-10 were not significantly different between the study groups.

CONCLUSIONS

In the present study, no significant differences were observed in the frequency of Th17 and Tr1 cells and in MFI of IL-17 and IL-10 in comparison to healthy individuals. Therefore, trying to make a change in the population of these cells probably does not have a significant therapeutic effect. Since Th2 cells and the expression of IFN-γ increased in women with HT, reducing the frequency of Th2 cells or the expression of IFN-γ may be effective in controlling the disease progression. It may be helpful for these patients to prevent the progression of the disease.

Clinical, biochemical, and radiological follow-up results of children and adolescents with Hashimoto's thyroiditis: a single-center experience

OBJECTIVES

Hashimoto's thyroiditis (HT) is the most common cause of goiter and acquired hypothyroidism in children and adolescents, especially in areas without endemic iodine deficiency. We aimed to evaluate the follow-up results of children and adolescents diagnosed with HT, including clinical, biochemical, and radiological findings and treatment approaches.

METHODS

HT patients, who were diagnosed between 2012 and 2018 years in a single-center, were assessed retrospectively.

RESULTS

Two hundred and twenty-four cases were included in the study, 75.9% of whom were girls (female/male ratio: 3.1) and 66.5% were pubertal. The median age of the cases at first admission was 12.5 (9.2-15) years. The median follow-up period of 196 patients, who continued their follow-up regularly, was 2.1 (0.7-4.8) years. When autoantibody levels were analyzed according to gender, mean anti-Tg levels were higher in girls (p=0.028), whereas anti-TPO levels were similar (p=0.372). A nodule was detected in the ultrasonographic follow-up of 29 (13%) patients. Papillary thyroid carcinoma was observed in 10.3% (n=3) of those with nodules. When the last ultrasonography findings of 188 patients with available radiological follow-up data were compared with their initial evaluation, the rate of heterogeneous parenchymal echogenicity increased significantly (p=0.008). The need for l-thyroxine dosage augmented over time.

CONCLUSIONS

Although HT is more common in adolescent girls, it can be encountered in both genders and at all ages in childhood. The incidence of malignancy was not higher in patients with nodules associated with HT than the reported incidences of malignancy in nodules not associated with HT.

Evaluation of the relationship between shear wave elastography measurements with laboratory and Doppler US parameters in patients with adult Hashimoto’s thyroiditis

Background/aim

Hashimoto thyroiditis (HT) is an autoimmune disease that leads to tissue stiffening secondary to lymphocyte infiltration of the thyroid gland. Gray-scale ultrasound (US) is widely used in its diagnosis. Numerous studies have been conducted comparing elastography findings of HT with tissue stiffness and immunoreactivity levels. This study aims to reveal the relationship between shear wave elastography (SWE) and Doppler parameters in patients with HT.

Materials and methods

The study group consisted of 45 patients diagnosed with HT, and 20 control patients without thyroid pathology. Thyroid-stimulating hormone (TSH) and antithyroid peroxidase (TPO) values were examined in patients with HT. Thyroid gland volume and echo patterns were evaluated in the gray-scale US. Doppler measurements –peak systolic velocity (Vmax), end-diastolic velocity (Vmin), pulsatility index (PI), resistivity index (RI)– from the superior thyroidal artery and SWE measurements were taken from both thyroid lobes.

Results

The mean age of men and women in the HT group was 44.8 and 43.4 years. The mean TSH value (normal value: 0.3–4.2 uIU/ mL) was 3.90 ± 6.6 uIU/mL, and the anti-TPO value (normal value: < 35 IU/mL) was 235.47 ± 271.12 IU/mL. The average thyroid gland volume was 10.12 ± 2.71 mL in the HT group and 6.62 ± 2.11 mL in the control group (P = 0.034). HT group mean Vmax, mean Vmin, mean PI and RI values were significantly lower compared to normal subjects (P = 0.022, P = 0.026, P = 0.042, P = 0.046, respectively). The average SWE value of the thyroid gland was 24.56 ± 18.04 kPa in the experimental group and 7.34 ± 3.54 (P < 0.05) in the control group.

Conclusion

A positive correlation was found between PI and RI values and elastography values. An increase in SWE and decreases in Vmax and Vmin were found as high diagnostic value for HT.

Shear-Wave Elastography-Diagnostic Value in Children with Chronic Autoimmune Thyroiditis

Chronic autoimmune thyroiditis (CAT) is the most common thyroid disorder in the pediatric population. Ultrasound evaluation may suggest the diagnosis. Additionally, shear-wave elastography (SWE) proved to be a valuable additional diagnosis tool in adults with CAT by assessing thyroid stiffness (TS). This study aims to assess its use also in detecting children with CAT. The study group consisted of 50 children with confirmed diagnosis of CAT, who were compared to the control group, consisting of 50 children with no thyroid pathology and with an adult group of 50 subjects with CAT. The evaluation included, besides bioimmunochemical evaluation, also thyroid ultrasound evaluation and elastography measurements in the same session (Aixplorer Mach 30, Supersonic imagine, France). The mean TS values were significantly lower for children in the CAT group compared to adults with CAT (15.51 ± 4.76 kPa vs. 20.96 ± 6.31 kPa; p < 0.0001) and higher compared to the healthy aged matched controls (15.51 ± 4.76 kPa vs. 10.41 ± 2.01 kPa; p < 0.0001). SWE elastography definitely seems a promising technique in the evaluation of children with autoimmune thyroid pathology.

Neutrophil and platelet to lymphocyte ratio in patients with hypothyroid Hashimoto's thyroiditis

AIM

Chronic lymphocytic thyroiditis is among the most common causes of hypothyroidism along with HT (Hashimoto's thyroiditis) goitre, which is also named as autoimmune thyroiditis. Our study aims to determine the usefulness of PLR (platelet to lymphocyte ratio) and NLR (neutrophil to lymphocyte ratio), which can be obtained with a hemogram, at the clinical course or the severity of the disease in patients with Hashimoto's thyroiditis.

MATERIALS AND METHODS

Our study is a retrospective cross-sectional study that included 121 hypothyroid or subclinical hypothyroid Hashimoto's thyroiditis patients and a healthy control group comprised of 100 individuals. Thyroid-stimulating hormone (TSH), free triiodothyronine (FT3), free thyroxine (FT4), anti-thyroid peroxidase (anti-TPO), complete blood count (CBC), and C-reactive protein (CRP) results were obtained from patient files for both HT patients and the control group, and we computed PLR and NLR for both groups.

RESULTS

PLR was lower in patients diagnosed with HT compared to the healthy control group, with statistical significance (respectively, 130.8±50.5 versus 145.3±58.5; p<0,05). NLR was higher in patients diagnosed with HT compared to the control group and a statistically significant relationship was determined (respectively, 2.43±0.94 versus 2,11±0,81; p<0,05). In addition to the present findings, we determined that PLR and NLR were correlated with anti-TPO, TSH, and FT4, although without statistical significance.

CONCLUSION

As values that can be measured with an inexpensive and easily accessible routine hemogram, PLR and NLR can serve as practical and valuable markers at the clinical course or the severity of the disease and other diseases that are autoimmune and progress with chronic inflammation.

Juvenile Hypothyroidism: A Clinical Perspective from Eastern India

INTRODUCTION

Juvenile hypothyroidism (JH) can have deleterious effects on growth, pubertal development, and scholastic performance of children. In India, there is a paucity of data on acquired hypothyroidism in children, in contrast to congenital hypothyroidism. Our objective was to assess the profile of JH in a referral clinic from eastern India.

MATERIALS AND METHODS

For this study, 100 patients with documented acquired hypothyroidism (subclinical and overt) (aged <18 years), from eastern India, were evaluated retrospectively. Evaluation included history as well as clinical, biochemical, and ultrasonography parameters.

RESULTS

Out of the 100 participants, 74% had overt hypothyroidism (OH), while 26% had subclinical hypothyroidism (SCH). The majority of the participants were females (66%). The mean age at detection was 8.95 ± 3.96 years in the SCH group and 8.38 ± 3.29 years in the OH group. A family history of thyroid disorder and/or goiter was present in 35% of the patients. Goiter was the most common presentation in both SCH and OH, with overall prevalence of 58%. Height below 3^rd percentile was significantly higher (28%) in OH group compared to 4% in SCH group. Five percent of OH subjects were obese. Worsening school performance was reported in only 9% of subjects. Only 4% (all males) presented with delayed puberty, while one female (1%) presented with precocious puberty. Sixty-four percent of OH group were TPOAb positive compared to only 15% in SCH group. Five percent of our study population had type-1 diabetes mellitus (T1DM) and 7% had Down syndrome (DS).

CONCLUSION

In our study, JH showed significantly higher female preponderance and TPOAb positivity in OH group, in comparison to SCH group. Family history of thyroid disorder and/or goiter was present in a significant proportion of patients. Goiter was the most common presentation of JH. Height deceleration, weight gain, and fatigue were the other common presentations. Prevalence of short stature was significantly higher in OH group. Interestingly, in contrast to prevalent notion, only 5% of OH were obese and worsening school performance was observed to be rare. Puberty disorders (both delayed and precocious) may occur in JH as seen here. Because of strong association, those with T1DM or DS should be screened for JH and vice versa in TIDM.

Local Ocular Surface Alterations in Children with Hashimoto's Thyroiditis

PURPOSE

To evaluate the ocular surface characteristics based on Schirmer's test, tear break-up time (TBUT), and conjunctival impression cytology (CIC) in children with Hashimoto's thyroiditis (HT).

METHODS

This study included 51 children with HT and 53 control subjects. The ocular surface characteristics of participants were assessed via Schirmer's test, TBUT, and CIC. Conjunctival samples were examined cytologically according to the Nelson grading system.

RESULTS

Schirmer's and TBUT results were significantly lower in HT group (p < .05). All samples in both the study and control groups were evaluated as grade 0 according to the Nelson classification (p = .841), however, goblet cell density (GCD) was significantly lower in HT group (p = .001). Schirmer test results were significantly associated with the duration of HT (p = .025, r = -0.311).

CONCLUSION

Hashimoto's thyroiditis without any ocular complaints may cause ocular surface changes with TBUT and Schirmer's. Although CIC analysis showed similar grading results, GCD was significantly decreased in HT group.

Evaluation and management of the child with hypothyroidism

BACKGROUND

Thyroid hormones are critical for early neurocognitive development as well as growth and development throughout childhood. Prompt recognition and treatment of hypothyroidism is, therefore, of utmost importance to optimize physical and neurodevelopmental outcomes.

DATA SOURCES

A PubMed search was completed in Clinical Queries using the key terms "hypothyroidism".

RESULTS

Hypothyroidism may be present at birth (congenital hypothyroidism) or develop later in life (acquired hypothyroidism). Thyroid dysgenesis and dyshormonogenesis account for approximately 85% and 15% of permanent cases of congenital primary hypothyroidism, respectively. More than 95% of infants with congenital hypothyroidism have few, if any, clinical manifestations of hypothyroidism. Newborn screening programs allow early detection of congenital hypothyroidism. In developed countries, Hashimoto thyroiditis is the most common cause of goiter and acquired hypothyroidism in children and adolescents. Globally, iodine deficiency associated with goiter is the most common cause of hypothyroidism. Central hypothyroidism is uncommon and may be associated with other congenital syndromes and deficiencies of other pituitary hormones. Familiarity of the clinical features would allow prompt diagnosis and institution of treatment.

CONCLUSIONS

To optimize neurocognitive outcome in infants with congenital hypothyroidism, treatment with levothyroxine should be started as soon as possible, preferably within the first 2 weeks of life. Children with acquired hypothyroidism should also be treated early to ensure normal growth and development as well as cognitive outcome. The target is to keep serum TSH < 5 mIU/L and to maintain serum free T4 or total T4 within the upper half of the age-specific reference range, with elimination of all symptoms and signs of hypothyroidism.

Effects of vitamin D supplements on frequency of CD4+ T-cell subsets in women with Hashimoto's thyroiditis: a double-blind placebo-controlled study

BACKGROUND

Vitamin D is a modulator of immune functions. Investigations on the mechanisms of vitamin D action and pathogenesis of Hashimoto's thyroiditis (HT) have revealed that vitamin D can reduce damages to thyroid cells caused by autoreactive immune cells.

METHODS

Totally, 48 female patients with HT disease were introduced to the study by endocrinologists. Patients were divided into two major groups of 24 individuals and treated weekly with 50,000 IU of cholecalciferol (vitamin D group) or placebo (placebo group) using oral administration for 3 months. Eventually, 17 of the 24 patients in each group finished the study. Before and after supplementation, frequencies of Th1, Th17, Th2 and Tr1 cells and mean fluorescent intensity (MFI) of the associated cytokines, including IFN-γ, IL-17, IL-4 and IL-10, were assessed using flow cytometry. Furthermore, gene expression of IL-10 was assessed using real-time PCR.

RESULTS

Results of this study showed that cholecalciferol supplementation caused a significant decrease in Th17/Tr1 ratio. The proportion and MFI of Th1, Th2, Tr1 and Th17 cells included no significant changes in vitamin D group, compared to those in placebo group. Expression rate and MFI of IL-10 increased in both groups. This increase was higher in vitamin D group than placebo group with no significance.

CONCLUSIONS

In this novel preliminary clinical trial study, supplementation with cholecalciferol in HT patients for 3 months changed the balance of CD4⁺ T-cell subsets to improve the disease control. However, further studies are necessary to investigate effects of vitamin D on immune functions in HT patients.

Hürthle cell metaplasia in chronic lymphocytic thyroiditis: Role of age factor and review of literature on its molecular pathogenesis

OBJECTIVES

Hürthle cell (HC) metaplasia is an important feature of chronic lymphocytic (Hashimoto) thyroiditis (HT). However, it is rarely observed in juvenile form HT. In a study based on fine needle aspiration cytology, the cytomorphological difference between pediatric HT and its adult form was studied, with special attention on HC metaplasia and its pathogenesis.

MATERIALS AND METHODS

The frequency of following 12 cytomorphological features in 16 pediatric and 104 adult HT cases were compared: follicular cells, lymphoid cells, HCs, plasma cells, lympho-histiocytic aggregates, epithelioid histiocytes, multinucleated giant cells, fire-flare appearance, colloid, intracytoplasmic lumen (ICL) with or without colloid inclusion, paravacuolar granules, and cyst cells. The age decade distribution of HC metaplasia was analyzed.

RESULTS

Significant difference was observed between pediatric HT and its adult form in respect of HC metaplasia and ICL with colloid inclusion in HC. HC were present in 7 (43.8%) of pediatric and 94 (90.4%) of adult HT cases (P = 0.00006). 1 (6.3%) pediatric and 35 (33.7%) adult HT cases had ICL with colloid inclusion in HC (P = 0.03698). As compared to first two decades of life, significantly higher number of cases revealed HC metaplasia in every decade from third decade onwards (P = 0.01290-0.00009); however, the difference in respect of ICL with colloid inclusions attained significance during sixth decade only (P = 0.00235).

CONCLUSIONS

Hürthlization, which appears to be survival response, is rare in pediatric HT and becomes more pronounced starting from third decade onwards; significant increase in ICL with colloid inclusion is a much more delayed phenomenon.

Association Kikuchi disease with Hashimoto thyroiditis: a case report and literature review

Kikuchi-Fujimoto disease (KFD) is a benign and self-limited disease characterized by fever and lymphadenopathy. The etiology of KFD is unknown, but an autoimmune cause has been suggested. Hashimoto thyroiditis is the most common autoimmune thyroid disorder in children and is known to be associated with other autoimmune diseases. Only a few cases of Hashimoto thyroiditis associated with KFD have been documented. We report a case of a 16-year-old girl who was first diagnosed with KFD and developed Hashimoto thyroiditis 2 years and 6 months later during her follow-up period. Physicians of patients with KFD should consider the possibility of autoimmune diseases like Hashimoto's thyroiditis.

Induction of hypothyroidism during early postnatal stages triggers a decrease in cognitive performance by decreasing hippocampal synaptic plasticity

Thyroid hormones are vital in the control of multiple body functions, including the correct performance of the brain. Multiple diseases are associated with thyroid gland functioning, including hypothyroidism. To date, little is known regarding the effects of the establishment of this condition at a young age on brain function. Here, we evaluated the effect of hypothyroidism in an early postnatal stage in cognitive abilities with focus on the hippocampus. In our model, hypothyroidism was induced in young rats at 21days of age using 0.05% 6-propyl-2-thiouracil (PTU) for 4weeks reaching significantly lower levels of fT₄ (control: 1.337ng/dL±0.115, PTU: 0.050ng/dL±0.001). Following the induction of hypothyroidism, several cognitive tasks were assessed to investigate the effects of hypothyroidism on cognition performance. We determined that hypothyroidism triggers a significant dysfunction in learning and memory processes observed in the Morris Water Maze were the latency times were higher in PTU rats (controls: 37s; PTU: 57s). The cognitive impairment was correlated with a reduction in hippocampal plasticity with respect to both long-term potentiation (LTP) (control: 1.45, PTU: 1.00) and depression (LTD) (control: 0.71, PTU: 1.01). Furthermore, a decrease in the rate of glucose utilization (control: 223nmol∗mg of protein, PTU:148nmol∗mg of protein) was observed, along with an increase in oxidative stress and a decrease in MAP2 marker in the hippocampus. Our findings suggest that the induction of hypothyroidism in a young rat model alters numerous functions at the level of the hippocampus.

Celiac disease in children and adolescents with Hashimoto Thyroiditis

AIM

The aim of this study was to evaluate clinical and laboratory findings and determine the prevalence of celiac disease (CD) in children with Hashimoto thyroiditis (HT).

MATERIAL AND METHODS

The data of a total of 80 patients with positive anti-thyroid antibodies who were aged between 6 and 17.9 years were retrospectively studied. Age, gender, complaints at the time of presentation, family history of thyroid disorders, clinical and laboratory findings were recorded. The levels of thyrotropin, free thyroxin, thyroid autoantibodies (thyroid peroxidase and thyroglobulin antibodies), immunoglobulin A (IgA), anti-tissue transglutaminase antibodies (IgA-tTG), and thyroid ultrasonography findings were enrolled.

RESULTS

Eighty patients (65 females (81.2%) and 15 males (18,8%)) were included in the study. Family history of thyroid disease was present in 38 (47.5%) patients. The most common complaints at the time of presentation were goiter (%30) and weight gain (%25). Forty three (53.8%), 23 (28.7%), and 14 (17.5%) patients presented with euthyroidism, subclinical hypothyroidism and obvious hypothyroidism. Thirty seven (46.2%) patients had goiter. IgA-tTG was found to be positive after a diagnosis of HT was made in only one patient (1.25%) and the diagnosis of CD was confirmed when intestinal biopsy of this patient revealed villus atrophy, crypt hyperplasia and increase in the intraepithelial lymphocyte count.

CONCLUSIONS

In our study, it was found that the most common complaints at presentation in patients with a diagnosis of hashimoto thyroiditis included goiter, weakness and weight gain and the prevalence of celiac diseases was found to be 1.25% (1/80). This study shows that the prevalence of CD in patients with a diagnosis of HT is higher compared to the prevalence in the healthy pediatric population.

Thyroid-related neurological disorders and complications in children

BACKGROUND

Thyroid hormones exert critical roles throughout the body and play an important and permissive role in neuroendocrine, neurological, and neuromuscular function.

METHODS

We performed a PubMed search through June 2014 with search terms including "hypothyroidism," "hyperthyroidism," "neurological complications," "neuropathy," "myopathy," "congenital hypothyroidism," and "encephalopathy." Relevant publications reviewed included case series, individual case reports, systematic reviews, retrospective analyses, and randomized controlled trials. The neurological outcomes of congenital hypothyroidism were reviewed, along with the clinical features of associated neuromuscular syndromes of both hypothyroidism and hyperthyroidism, including other autoimmune conditions. Evidence for, and pathophysiological controversies surrounding, Hashimoto encephalopathy was also reviewed.

RESULTS

The establishment of widespread newborn screening programs has been highly successful in attenuating or preventing early and irreversible neurological harm resulting from congenital thyroid hormone deficiency, but some children continue to display neuromuscular, sensory, and cognitive defects in later life. Acquired disorders of thyroid function such as Hashimoto thyroiditis and Graves' disease are associated with a spectrum of central nervous system and/or neuromuscular dysfunction. However, considerable variation in clinical phenotype is described, and much of our knowledge of the role of thyroid disease in childhood neurological disorders is derived from adult case series.

CONCLUSIONS

Early and aggressive normalization of thyroxine levels in newborn infants with congenital hypothyroidism is important in minimizing neurological sequelae, but maternal thyroid hormone sources are also critically important to the early developing brain. A spectrum of neurological disorders has been reported in older children with acquired thyroid disease, but the frequency with which these occur remains poorly defined in the literature, and much must be extrapolated from adult data. A high index of suspicion for acquired thyroid disease is paramount in the investigation of many neurological disorders of youth, as many reported sequelae of hypothyroidism and hyperthyroidism are reversible with appropriate endocrine management.

Low Growth Hormone Levels in Short-Stature Children with Pituitary Hyperplasia Secondary to Primary Hypothyroidism

Objective. The follow-up of GH levels in short-stature children with pituitary hyperplasia secondary to primary hypothyroidism (PPH) is reported in a few cases. We aimed to observe changes in GH secretion in short-stature children with PPH. Methods. A total of 11 short-stature children with PPH accompanied by low GH levels were included. They received levothyroxine therapy after diagnosis. Their thyroid hormones, IGF-1, PRL, and pituitary height were measured at baseline and 3 months after therapy. GH stimulation tests were performed at baseline and after regression of thyroid hormones and pituitary. Results. At baseline, they had decreased GH peak and FT3 and FT4 levels and elevated TSH levels. Decreased IGF-1 levels were found in seven children. Elevated PRL levels and positive thyroid antibodies were found in 10 children. The mean pituitary height was 14.3 ± 3.8 mm. After 3 months, FT3, FT4, and IGF-1 levels were significantly increased (all p < 0.01), and values of TSH, PRL, and pituitary height were significantly decreased (all p < 0.001). After 6 months, pituitary hyperplasia completely regressed. GH levels returned to normal in nine children and were still low in two children. Conclusion. GH secretion can be resolved in most short-stature children with PPH.

The natural course of Hashimoto's thyroiditis in children and adolescents

OBJECTIVE

Hashimoto's thyroiditis (HT) is the most common cause of thyroid disease in children and adolescents, but little is known about the long-term follow-up of HT. The aim of this study was to analyze the clinical and laboratory characteristics and to observe the natural course of HT in children and adolescents.

METHODS

We retrospectively reviewed 153 patients with HT diagnosed before 18 years of age. Subjects were grouped into euthyroid, subclinical hypothyroidism, overt hypothyroidism, and hyperthyroidism on the basis of the thyroid function test. Of the 153 subjects, 133 were followed up (range 6∼181 months) at our clinic every 6 months for evaluation of goiter size, thyroid function, thyroid peroxidase antibodies (TPO Ab), and thyroglobulin antibodies (TG Ab) serum concentration.

RESULTS

Thyroid function tests at the time of presentation revealed euthyroid in 72 patients (47.1%), subclinical hypothyroidism in 48 (31.4%), overt hypothyroidism in 22 (14.4%), and hyperthyroidism in 11 (7.2%). Serum TPO Ab and TG Ab significantly decreased in the subclinical hypothyroidism group with levothyroxine treatment. Also, there was a significant decrease in the mean serum TG Ab levels among the overt hypothyroid patients during the follow-up period, although TPO Ab levels were not significantly different when compared to their baseline TPO Ab levels.

CONCLUSION

Most children with HT were euthryoid and remained euthyroid during follow-up. However, thyroid function should still be monitored periodically for early detection and treatment of overt hypothyroidism. Our data also showed that levothyroxine treatment may have beneficial effects on the thyroid antibody titers.

Hashimoto thyroiditis: clinical and diagnostic criteria

Hashimoto thyroiditis (HT), now considered the most common autoimmune disease, was described over a century ago as a pronounced lymphoid goiter affecting predominantly women. In addition to this classic form, several other clinico-pathologic entities are now included under the term HT: fibrous variant, IgG4-related variant, juvenile form, Hashitoxicosis, and painless thyroiditis (sporadic or post-partum). All forms are characterized pathologically by the infiltration of hematopoietic mononuclear cells, mainly lymphocytes, in the interstitium among the thyroid follicles, although specific features can be recognized in each variant. Thyroid cells undergo atrophy or transform into a bolder type of follicular cell rich in mitochondria called Hürthle cell. Most HT forms ultimately evolve into hypothyroidism, although at presentation patients can be euthyroid or even hyperthyroid. The diagnosis of HT relies on the demonstration of circulating antibodies to thyroid antigens (mainly thyroperoxidase and thyroglobulin) and reduced echogenicity on thyroid sonogram in a patient with proper clinical features. The treatment remains symptomatic and based on the administration of synthetic thyroid hormones to correct the hypothyroidism as needed. Surgery is performed when the goiter is large enough to cause significant compression of the surrounding cervical structures, or when some areas of the thyroid gland mimic the features of a nodule whose cytology cannot be ascertained as benign. HT remains a complex and ever expanding disease of unknown pathogenesis that awaits prevention or novel forms of treatment.

Serum concentrations of anti-thyroid peroxidase and anti-thyroglobulin antibodies in children and adolescents without apparent thyroid disorders

OBJECTIVE

The age-dependent prevalence and clinical relevance of anti-thyroid peroxidase (TPOAb) and anti-thyroglobulin (TGAb) antibodies in children and adolescents without thyroid diseases are unknown. The aim of this study was to measure the concentration of these thyroid autoantibodies in a large cohort of hospitalized and out-patient subjects. Additionally, we investigated the correlation of TPOAb and TGAb with thyroid parameters as well as with putative confounding parameters such as standard deviation scores (SDS) of height, BMI-SDS and CRP.

METHODS

Serum samples from 841 patients with non-thyroid related diseases between 1 day post partum and 20 years of age were used in a cross-sectional study. TPOAb, TGAb, thyroid parameters (TSH, fT3, fT4 and thyroglobulin) and CRP were measured by the Modular System (Roche, Mannheim).

RESULTS

The values of TPOAb and TGAb showed an age-dependent maximum of antibody frequency for both genders during the first year of life with concentrations of 163 IU/mL and 161 IU/mL in the 95th percentile. In girls, a second maximum was observed during puberty with concentrations of 82 IU/mL TPOAb and 582 IU/mL TGAb in the 95th percentile. Both antibodies correlated significantly (p<0.05) with each other, with fT3, fT4, BMI-SDS (only TPOAb) and CRP and TSH (only TGAb).

CONCLUSION

The prevalence of TPOAb and TGAb was shown to be age-dependent with increased values in the first year of life and during puberty. The increased "physiological" concentrations of TPOAb and TGAb have to be considered when used as diagnostic indicators of autoimmune thyroid disease in a paediatric population.

The role of the resistive index in Hashimoto's thyroiditis: a sonographic pilot study in children

OBJECTIVE

The role of Doppler ultrasonography in the diagnosis of diffuse thyroid diseases is not well established. In particular, Doppler ultrasonography findings in children with Hashimoto's thyroiditis are very limited. We examined gray-scale and Doppler ultrasound findings in Hashimoto's thyroiditis in children in an attempt to understand the feasibility of future prospective controlled studies.

MATERIALS AND METHODS

Twenty-one children with newly diagnosed Hashimoto's thyroiditis were recruited in the study. The patients were euthyroid or had subclinical hypothyroidism at the time of the ultrasonography examination. According to the color Doppler scale developed by Schulz et al., thyroid glands were classified into four patterns based on visual scoring and the mean resistive index (RI), which was calculated via measurements from both lobes, and these results were compared with gray-scale findings.

RESULTS

The mean RI value, calculated as the mean of the RI values of both lobes obtained from each patient, was found to be 0.57 ± 0.05 (range 0.48-0.67) cm/sn. The distribution of thyroid classifications was as follows: Pattern 0, n = 7; Pattern I, n = 6; Pattern II, n = 4; and Pattern III ("thyroid inferno"), n = 4. The mean RI values in patients with normal or near-normal gray-scale findings (n = 10) and patients with more substantial gray-scale changes (n = 11) were not significantly different and were lower than the values in normal children previously presented in the literature.

CONCLUSION

The results indicated that the RI may be more sensitive than other ultrasound parameters for the diagnosis of Hashimoto's thyroiditis.

WITHDRAWN: A female autoimmunity gene exists: DDX3X

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Evaluation of thyroid functions with respect to iodine status and TRH test in chronic autoimmune thyroiditis

OBJECTIVE

Chronic autoimmune thyroiditis (CAT) is the most common form of thyroiditis in childhood and a frequent cause of acquired hypothyroidism. The objective of this study was to evaluate the thyroid status of children and adolescents with CAT with respect to iodine status and diagnostic values of thyrotropin-releasing hormone (TRH) test.

METHODS

Seventy-one children (mean age: 11.6 years) were studied in a retrospective analysis. Free thyroxine (T4), thyrotropin (TSH), TSH response to TRH test, thyroid autoantibodies, thyroid sonography, and urinary iodine excretion (UIE) were evaluated.

RESULTS

At diagnosis, 8.5% of patients had overt hypothyroidisim and 36.6% subclinical hypothyroidism; 5.6% had overt hyperthyroidisim and 8.5% had subclinical hyperthyroidism. Of them, 40.8% were euthyroid. Median UIE was 51 mg/L in overt hypothyroidism and 84 mg/L in subclinical hypothyroidism. The values were 316 mg/L and 221 mg/L in overt and subclinical hyperthyroidism, respectively. Basal TSH showed a strong correlation with peak TSH level on TRH test. Thirty-four percent of patients with normal basal TSH level showed an exaggerated TSH response.

CONCLUSION

Iodine deficiency was seen more in cases with hypothyroidism, while excess of iodine was observed to be more frequent in hyperthyroid patients. Iodine status was a strong predictorof the thyroid status in CAT. TRH test may be helpful in further delineating patients with subclinical hypothyroidism.

The frequency of Hashimoto thyroiditis in children and the relationship between urinary iodine level and Hashimoto thyroiditis

The aim of this study was to determine the frequency of thyroid autoimmunity in second grade primary school students and to examine the relationship between iodine and Hashimoto thyroiditis (HT). This was a cohort study performed with 1000 students. Urinary iodine levels, antithyroid peroxidase (anti-TPO) and antithyroglobulin (anti-Tg) antibodies were determined in all children. Children with anti-TPO or anti-Tg antibody positivity or with goiter were summoned for detailed examinations. In total, 36 cases (3.6%) were diagnosed as HT. The goiter frequency was found in 17.5% of the whole cohort. Additionally, iodine deficiency was found in 64.2% of all children. The median urinary iodine excretion was determined as 132 microg/L (range 382 microg/L) in the HT group, whereas it was 73 microg/L (range 390 microg/L) in children with goiter but without HT and 81 microg/L (range 394 microg/L) in normal children. The urinary iodine level of HT cases was significantly higher than the other two groups (p < 0.001). HT was also determined in 2% of patients with low urinary iodine levels, in 6.2% of patients with normal urinary iodine levels, and in 7.5% of patients with high urinary iodine levels. Our data demonstrates the close relationship between excessive iodine levels and autoimmunity.

Fine-needle aspiration in the evaluation of thyroid lesions in children

The role of fine-needle aspiration (FNA) cytology in the evaluation of thyroid lesions in not as well established in children when compared with adults. Hence we aimed to ascertain the utility and limitations of FNA in childhood thyroid lesions. This was a retrospective analysis of all thyroid FNA performed in children less than 14 years of age over a 4-year period (2005-2009). Histopathological follow-up was available in six cases. A total of 77 cases were included in the analysis. The most common cytological diagnosis was lymphocytic thyroiditis (49.3%), followed by colloid goiter (18.2%), hyperplasia (10.4%), and benign aspirate (7.8%); malignancy was identified in six cases (7.8%). Of these six cases, three were papillary thyroid carcinoma. There was one false-positive case reported as a Hurthle-cell neoplasm, which on histology showed Hashimoto's thyroiditis. One case each of rhabdomyosarcoma and spindle epithelial tumor with thymus like differentiation was wrongly diagnosed as thyroid neoplasm, NOS, and medullary carcinoma (spindle variant), respectively. The overall diagnostic accuracy was 98.6% with 100% sensitivity, 98.6% specificity, 80% positive predictive value, and 100% negative predictive value. FNA is extremely valuable in the initial evaluation of thyroid swelling in children. Rare neoplasms masquerading as thyroid nodules in children can pose difficulties in diagnosis; however, papillary carcinoma is easily recognized. In lymphocytic thyroiditis, it provides a tissue diagnosis, thereby avoiding more invasive procedure for merely diagnostic purposes.

Pituitary hyperplasia in children with short stature and primary hypothyroidism

We present eight cases with short stature, pituitary hyperplasia, and hypothyroidism. Pituitary hyperplasia due to primary hypothyroidism was diagnosed on the basis of clinical manifestations, endocrine examination and MRI. After 2 to 6 months of L-thyroxine replacement therapy, the signs of hypothyroidism disappeared; free triiodothyronine, free thyroxine, thyrotropin and prolactin became normal; and pituitary enlargement regressed. In two children, the growth rate remained low when treated with L-thyroxine, but with additional recombinant human growth hormone (rhGH), the height increased by 11 cm per year. No recurrence of lesions was found on follow-up.

Hashimoto encephalopathy in a 15-year-old-girl: EEG findings and follow-up

Hashimoto encephalopathy is characterized by severe neuropsychiatric findings, including psychosis, confusion, seizures, stupor, stroke-like episodes, tremor, and myoclonus. The combination of findings is variable. Hashimoto encephalopathy constitutes an important differential diagnosis in patients with encephalopathy. The triad of encephalopathy, corresponding electroencephalographic slowing, and increased protein content in cerebrospinal fluid should prompt testing of anti-thyroid antibodies in blood and cerebrospinal fluid. Elevated antibody levels support the diagnosis. We describe a 15-year-old girl with a fluctuating course of Hashimoto encephalopathy. Electroencephalograms revealed no specific alterations, but widespread slowing of the background activity occurred during two episodes of fluctuating encephalopathy. Cortical edema was indicated by cranial magnetic resonance imaging during the first episode of encephalopathy, in the context of cerebral seizures. Laboratory findings were in accordance with Hashimoto encephalopathy, which was steroid-responsive.

Prevalence of autoimmune thyroiditis in children with celiac disease and effect of gluten withdrawal

OBJECTIVE

To study the prevalence of autoimmune thyroiditis (AT) in Sardinian children with celiac disease (CD) and the effects of a gluten-free diet (GFD) on thyroid function.

STUDY DESIGN

Children with biopsy-proven CD (n = 324; female:male 2:1; mean age, 6.6 years) followed from 1 to 15 years, were retrospectively evaluated for AT at onset of CD and during GFD. Serum thyroid peroxidase and thyroglobulin antibodies (AbTPO, AbTG), thyroid-stimulating hormone (TSH), free thyroxine (FT4), free triiodothyronine (FT3), and thyroid ultrasonography were considered. Age-matched Sardinian schoolchildren (n = 8040), previously evaluated for antithyroid antibodies and thyroid function, were used as controls.

RESULTS

Thirty-four patients with CD (10.5%) developed AT (female:male 4,5:1; mean age, 10.5 years), 11 at onset of CD and 23 during GFD, with a higher prevalence than controls (P = 2.9(-13)). Twenty-eight patients were euthyroid and 6 hypothyroid. AbTPO and/or AbTG persisted elevated for 2 to 9 years despite the GFD in 9 of 11 patients with AT at onset of CD.

CONCLUSIONS

AT is strongly associated with CD in Sardinian children, has an age of onset of 10.5 years, and appears to be gluten-independent. In children with CD with AT, the female:male bias reported in adult AT is present before puberty.

Complement 4 phenotypes and genotypes in Brazilian patients with classical 21-hydroxylase deficiency

The aim of this work was to analyse C4 genotypes, C4 protein levels, phenotypes and genotypes in patients with the classical form of 21-hydroxylase deficiency. Fifty-four patients from 46 families (36 female, 18 male; mean age 10.8 years) with different clinical manifestations (31 salt-wasting; 23 simple-virilizing) were studied. Taq I Southern blotting was used to perform molecular analysis of the C4/CYP21 gene cluster and the genotypes were defined according to gene organization within RCCX modules. Serum C4 isotypes were assayed by enzyme-linked immunosorbent assay. The results revealed 12 different haplotypes of the C4/CYP21 gene cluster. Total functional activity of the classical pathway (CH50) was reduced in individuals carrying different genotypes because of low C4 concentrations (43% of all patients) to complete or partial C4 allotype deficiency. Thirteen of 54 patients presented recurrent infections affecting the respiratory and/or the urinary tracts, none of them with severe infections. Low C4A or C4B correlated well with RCCX mono-modular gene organization, but no association between C4 haplotypes and recurrent infections or autoimmunity was observed. Considering this redundant gene cluster, C4 seems to be a well-protected gene segment along the evolutionary process.