Autoimmune hypothyroidism coexisting with a pituitary adenoma secreting thyroid-stimulating hormone, prolactin and alpha-subunit

Coexistence of TSH-secreting adenoma and primary hypothyroidism: a case report and review of literature

BACKGROUND

Thyrotropin-secreting adenoma (TSHoma) is the least common type of pituitary adenoma, these patients often present with symptoms of hyperthyroidism. When TSHoma patients combined with autoimmune hypothyroidism, it is critically difficult to diagnose for the specific confusion in the results of thyroid function test.

CASE PRESENTATION

One middle-aged male patient was presented with a sellar tumor on cranial MRI for headache symptoms. After hospitalization, a significant increase in thyrotropin (TSH) was revealed by the endocrine tests, while free thyronine (FT3) and free thyroxine (FT4) decreased, and the diffuse destruction of thyroid gland was revealed by thyroid ultrasound. Based on the endocrine test results, the patient was diagnosed as autoimmune hypothyroidism. After the multidisciplinary discussion, the pituitary adenoma was removed by endoscopic transnasal surgery, until the tumor was completely excised, for which TSHoma was revealed by postoperative pathology. A significant decrease of TSH was revealed by the postoperative thyroid function tests, the treatment for autoimmune hypothyroidism was conducted. After 20 months of follow-up, the thyroid function of patient had been improved significantly.

CONCLUSION

When the thyroid function test results of patients with TSHoma are difficult to interpret, the possibility of combined primary thyroid disease should be considered. TSHoma combined with autoimmune hypothyroidism is rare, which is difficult to diagnose. The multidisciplinary collaborative treatment could help to improve the outcomes of treatment.

Pituitary Macroadenoma Secondary to Congenital Hypothyroidism With Growth Failure and Developmental Delay: A Rare Presentation

Reactive pituitary hyperplasia can develop as a pituitary (pseudo) macroadenoma in the case of primary hypothyroidism. Hypothyroidism-induced pituitary hyperplasia (PHPH) can be managed medically. Surgery should not be performed if this condition is misdiagnosed as an adenoma. Primary hypothyroidism is a well-known cause of children's slow linear growth. Anterior pituitary enlargement is a rare symptom of severe or long-term illness (pituitary pseudotumor). Thyroid-stimulating hormone-secreting adenomas (TSHomas) are the rarest type of pituitary adenomas, with most endocrinologists seeing just a few cases throughout their lives. In most situations, the diagnosis is difficult, and patients may be referred after presenting with a condition of excessive thyroid-stimulating hormone secretion or a pituitary tumor. In this case study, we describe a 3.5-year-old girl who was referred to our hospital for a surgical assessment of a suspected pituitary neoplastic lesion. It was later determined that the suspected lesion was really pituitary hyperplasia brought on by primary hypothyroidism. Levothyroxine was started, and the dose was increased. The patient was advised to follow up to see if pituitary macroadenoma had responded to levothyroxine supplementation. Pituitary enlargement (pseudotumor of the pituitary gland) is a rare complication of primary hypothyroidism. Early diagnosis and treatment are critical for children with severe primary hypothyroidism to maintain their final height, as late diagnosis nearly always leads to a decline in adult stature. Pituitary macroadenoma secondary to severe hypothyroidism does not need risky and expensive surgical intervention. Because PHPH is rare in children, more credible information is needed to have a better knowledge of how the disease progresses and to develop scientific diagnostic criteria.

Primary hypothyroidism in a child leads to pituitary hyperplasia: A case report and literature review

RATIONALE

A sellar mass in children is most often seen in craniopharyngeal tumors, intracranial germ cell tumors, or pituitary adenomas. However, pituitary hyperplasia secondary to primary hypothyroidism (PHPH) is not commonly seen in children.

PATIENT CONCERNS

A 10-year-old girl was admitted due to growth retardation and obesity for 4 years. On physical examination, the patient had a height of 118 cm, body weight of 46 kg, body mass index (BMI) of 33.0 kg/m.

DIAGNOSES

After magnetic resonance imaging (MRI) and laboratory tests, her initial diagnosis was Hashimoto's thyroiditis, primary hypothyroidism, and reactive pituitary hyperplasia.

INTERVENTIONS

She was treated with oral L-thyroxine tablets.

OUTCOMES

After 6 months, physical examination showed a height of 125 cm, weight of 36 kg, BMI of 23.0 kg/m. She developed well, with 12 cm of yearly growth thereafter.

LESSONS

The diagnosis of PHPH in a child is very important and sometimes difficult. Based on the summary and analysis of previous cases, we can learn that the main manifestations of PHPH include growth arrest and obesity, perhaps accompanied by symptoms caused by a decreased thyroid hormone concentration and elevated prolactin (PRL) concentration. Intracranial MRI shows diffuse enlargement of the anterior lobe of the pituitary gland, with a dome-shaped blunt edge change. Thyroid hormone levels may decrease, whereas the thyroid stimulating hormone (TSH) level increases, commonly accompanied by an elevated PRL, reduced growth hormone (GH) levels, and positive findings of TPOAb and TGAb. Improvement of symptoms and the normalization of hormone levels as well as restoration of pituitary size can be achieved after treated with thyroid hormone replacement therapy. And a hasty decision on surgical resection should be avoided when the diagnosis is uncertain.

Emergence of a latent TSHoma pituitary macroadenoma on a background of primary autoimmune hypothyroidism

The coexistence of primary hypothyroidism and thyroid-stimulating hormone (TSH)-stimulating pituitary macroadenoma can be a rare occurrence and can make diagnosis very challenging. We describe a case of a 44-year-old female with a history of fatigue, poor concentration, weight gain and amenorrhoea together with biochemical evidence of primary autoimmune hypothyroidism. Her initial TSH levels were elevated with low normal free thyroxine (T4) levels. Levothyroxine treatment was initiated and the dose was gradually titrated to supraphysiologic doses. This led to the normalisation of her TSH levels but her free T4 and triiodothyronine (T3) levels remained persistently elevated. This prompted a serum prolactin check which returned elevated at 2495 μ/L, leading onto pituitary imaging. A MRI of the pituitary gland revealed a pituitary macroadenoma measuring 2.4 × 2 × 1.6 cm. Despite starting her on cabergoline therapy with a reduction in her prolactin levels, her TSH levels began to rise even further. Additional thyroid assays revealed that she had an abnormally elevated alpha subunit at 3.95 (age-related reference range <3.00). This corresponded to a thyroid-secreting hormone pituitary macroadenoma. She went on to have a transphenoidal hypophysectomy. Histology revealed tissues staining for TSH, confirming this to be a TSH-secreting pituitary macroadenoma. This case highlighted the importance of further investigations with thyroid assay interferences, heterophile antibodies, alpha subunit testing and anterior pituitary profile in cases of resistant and non-resolving primary hypothyroidism. Learning points: •• Levothyroxine treatment in primary hypothyroidism can potentially unmask the presence of a latent TSH-secreting pituitary macroadenoma, which can make diagnosis very challenging. •• A high index of suspicion should prompt clinicians to further investigate cases of primary hypothyroidism which despite increasing doses of levothyroxine treatment with normalisation of TSH, the free T4 and T3 levels remain persistently elevated. •• Clinicians should consider investigating for adherence to levothyroxine, thyroid assay interference, heterophile antibodies, TSH dilution studies, alpha subunit and anterior pituitary profile testing to further clarity the diagnosis in these patients. •• Although coexistent cases of TSHoma with primary hypothyroidism are rare, it should always be in the list of differential diagnoses in cases of unresolving primary hypothyroidism.

Thyrotropin-secreting pituitary adenomas: epidemiology, diagnosis, and management

Inappropriate secretion of TSH was first described in 1960 in a patient with evidence of hyperthyroidism and expanded sella on imaging. It was later found that a type of pituitary adenoma that secretes TSH (thyrotropinoma) was the underlying cause. The objective of the present review article is to summarize data on the epidemiology, pathogenesis, diagnosis, and management of thyrotropinomas. The prevalence of thyrotropinomas is lower than that of other pituitary adenomas. Early diagnosis is now possible thanks to the availability of magnetic resonance imaging and sensitive laboratory assays. As a corollary, many patients now present earlier in the course of their disease and have smaller tumors at the time of diagnosis. Treatment also has evolved over time. Transsphenoidal surgery is still considered definitive therapy. Meanwhile, radiation therapy, including radiosurgery, is effective in achieving tumor control in the majority of patients. In the past, radiation therapy was used as second line treatment in patients with residual or recurrent tumor after surgery. However, the availability of somatostatin analogs, which can lead to normalization of thyroid function as well as shrink these tumors, has led to an increase in the role of medical therapy in patients who are not in remission after pituitary surgery. In addition, dopamine agonists have shown some efficacy in the management of these tumors. Better understanding of the molecular pathogenesis of thyrotropinomas may lead to rationally designed therapies for patients with thyrotropinomas.

Pitfalls in the measurement and interpretation of thyroid function tests

Thyroid function tests (TFTs) are amongst the most commonly requested laboratory investigations in both primary and secondary care. Fortunately, most TFTs are straightforward to interpret and confirm the clinical impression of euthyroidism, hypothyroidism or hyperthyroidism. However, in an important subgroup of patients the results of TFTs can seem confusing, either by virtue of being discordant with the clinical picture or because they appear incongruent with each other [e.g. raised thyroid hormones (TH), but with non-suppressed thyrotropin (TSH); raised TSH, but with normal TH]. In such cases, it is important first to revisit the clinical context, and to consider potential confounding factors, including alterations in normal physiology (e.g. pregnancy), intercurrent (non-thyroidal) illness, and medication usage (e.g. thyroxine, amiodarone, heparin). Once these have been excluded, laboratory artefacts in commonly used TSH or TH immunoassays should be screened for, thus avoiding unnecessary further investigation and/or treatment in cases where there is assay interference. In the remainder, consideration should be given to screening for rare genetic and acquired disorders of the hypothalamic-pituitary-thyroid (HPT) axis [e.g. resistance to thyroid hormone (RTH), thyrotropinoma (TSHoma)]. Here, we discuss the main pitfalls in the measurement and interpretation of TFTs, and propose a structured algorithm for the investigation and management of patients with anomalous/discordant TFTs.

When thyroid hormone replacement is ineffective?

PURPOSE OF REVIEW

In this article, we will consider the failure of thyroid hormone replacement therapy to normalize serum thyroid stimulating hormone concentrations. We will review circumstances and causes for failures, discuss pertinent unpublished personal cases of didactical value, and provide practical suggestions for providers encountering patients with similar presentations.

RECENT FINDINGS

Recent data are available on the benefit of novel formulations of levothyroxine therapy on malabsorption.

SUMMARY

Most frequently, reasons for ineffectiveness are noncompliance, inappropriate administration of levothyroxine, gastrointestinal disorders, and drug interactions. The diagnostic work-up should include careful history to elucidate the potential reasons for the ineffective therapy.

Coexistence of TSH-secreting pituitary adenoma and autoimmune hypothyroidism

OBJECTIVE

TSH-secreting pituitary adenomas account for about 1-2% of all pituitary adenomas. Their diagnosis may be very difficult when coexistence of other diseases masquerades the clinical and biochemical manifestations of TSH-hypersecretion.

CLINICAL PRESENTATION

A 41-yr-old female patient, weighing 56 kg, was referred for evaluation of an intra- and suprasellar mass causing menstrual irregularities. Eight yr before, the patient had been given a diagnosis of subclinical autoimmune hypothyroidism because of slightly elevated TSH levels and low-normal free T4 (FT4). Menses were normal. Despite increasing doses of levo-T4 (L-T4; up to 125 microg/day), TSH levels remained elevated and the patient developed mild symptoms of hyperthyroidism. After 7 yr, the menstrual cycle ceased. Gonadotropins were normal, whereas PRL level was elevated at 70 microg/l and magnetic resonance imaging (MRI) of the hypothalamic- pituitary region revealed a pituitary lesion with slight suprasellar extension. The tumor was surgically removed and histological examinations revealed a pituitary adenoma strongly positive for TSH. Three months after surgery the patient was well while receiving L-T4 75 microg/day and normal menses had resumed. MRI of the hypothalamic-pituitary region showed no evidence of residual tumor. At the last follow-up, 16 months after surgery, serum TSH, free T3 (FT3), and FT4 levels were normal.

CONCLUSIONS

Coexistence of autoimmune hypothyroidism and TSH-secreting pituitary adenoma may cause further delays in the diagnosis of the latter. In patients with autoimmune hypothyroidism, one should be aware of the possible presence of a TSH-secreting pituitary adenoma when TSH levels do not adequately suppress in the face of high doses of L-T4 replacement therapy and elevated serum thyroid hormone levels.