ABSTRACT
BACKGROUND AND OBJECTIVE: Thyrotoxicosis is a common clinical condition encountered in endocrine practice. Graves' disease and subacute thyroiditis are the two common causes of thyrotoxicosis and often have overlapping clinical and biochemical features. 99mTc thyroid scintigraphy is the most commonly used confirmatory test to differentiate the two conditions but is not available in the majority of the second-tier cities of India. However, obtaining thyroid stimulating hormone (TSH) receptor antibodies (TSHrAb), another accurate test to differentiate the two conditions, in second-tier cities by outsourcing to labs in major cities is a feasible option nowadays. However, the data on the performance of TSHrAb to differentiate the two conditions in Indian patients is limited. Hence, we have evaluated the diagnostic accuracy of TSHrAb in the Indian population to differentiate Graves' disease and subacute thyroiditis. MATERIALS AND METHODS: This prospective study was conducted on 115 consecutive newly diagnosed thyrotoxicosis patients presenting to the Department of Endocrinology at a tertiary health care centre in India. Clinical parameters like throat pain, duration of symptoms, and grade of goitre were noted. Measurement of total tri-iodothyronine (TT3), total thyroxine (TT4), TSH, TSHrAb, and 99mTc thyroid scintigraphy were performed in all participants. All participants were followed up at least for six months after the recruitment. Increased tracer uptake (>4%) and/or increased thyroid to parotid trace uptake ratio (>2.5) were used to diagnose Graves' disease. RESULTS: Eighty-one and 34 patients were diagnosed with Graves' disease and subacute thyroiditis, respectively. TT3/TT4 ratio had low diagnostic accuracy (area under the curve (AUC): 0.6, best cut-off: 15.6, sensitivity: 53.1%, specificity: 79.4%). TSHrAb had the best AUC (0.9) to distinguish Graves' disease from subacute thyroiditis (cut-off: 2.0 IU/L, sensitivity: 97.5%, specificity: 100%). In contrast, the kit manufacturer's reference range (1.75 IU/L) was slightly more sensitive (98.8%), but less specific (94%). CONCLUSION: The TT3/TT4 ratio is not a good test to differentiate Graves' disease and subacute thyroiditis. TSHrAb is accurate in distinguishing Graves' disease from subacute thyroiditis and a level of 2.0 may be a more accurate cut-off to differentiate the two conditions in the Indian population.
ABSTRACT
Ectopic adrenocorticotropic hormone (ACTH) syndrome (EAS) is rare in children, and localizing the source of EAS is often challenging. Here, we report EAS in an adolescent boy who presented with Cushingoid features and had endogenous ACTH-dependent hypercortisolism on hormonal evaluation. Abdominal ultrasound and CT revealed a hepatic lesion with characteristics suggestive of hemangioma, whereas the lesion was tracer non-avid on 68Ga-DOTANOC positron emission tomography/CT. A regional sampling of ACTH was done to confirm the hepatic lesion as the source of EAS, and a definitive ACTH gradient was observed between the hepatic vein and the right internal jugular vein. Further, a preoperative biopsy of the lesion revealed a small round cell tumor with positive immunostaining for ACTH and synaptophysin, suggestive of a neuroendocrine tumor. The patient was managed with partial hepatectomy, resulting in hormonal and clinical remission of Cushing syndrome. In a systematic review of pediatric EAS due to primary hepatic tumors (n = 11), calcifying nested stromal epithelial cell tumors were the most common. EAS-associated hepatic tumors were larger (≥10 cm) except benign primary hepatic neuroendocrine tumors (PHNET). The latter were misdiagnosed as hemangioma in two cases by anatomical imaging but correctly diagnosed by somatostatin receptor scintigraphy. Hepatic tumors causing EAS in children required extensive resection, except benign PHNET. Nevertheless, all benign tumors with an uncomplicated perioperative course demonstrated disease-free survival over a median follow-up period of two years.
ABSTRACT
The data on the characteristics of patients with idiopathic intracranial hypertension (IIH) following levothyroxine (LT4) replacement are limited. Here, we report a case and systematically review published cases of idiopathic intracranial hypertension (IIH) following levothyroxine (LT4) replacement. The systematic review was performed as per the PRISMA guidelines. Our patient is a 46-year-old lady with hypothyroidism (thyrotropin: 319 mIU/L, free thyroxine: 0.04 ng/dl), treated with 100 µg.d of LT4 and presented a month later with headache, visual diminution, bilateral lateral rectus palsies, and papilledema. Cerebrospinal fluid (CSF) pressure was 32 cmH2O. Drainage of CSF, oral acetazolamide, and modification of LT4 dose resulted in prompt symptomatic improvement and complete reversal of IIH. In the systematic review (n = 21), the median age of patients (7 males) was 13 (IQR: 8.8- 26.5) years. The median duration of hypothyroid symptoms was 4 (n = 10, IQR: 0.44-6.25) years whereas that from initiation of LT4 replacement to the diagnosis of IIH was 2 (n = 20, IQR: 1.17-4) months. Initial median serum thyrotropin and thyroxine were 100 (n = 14, IQR: 72.5-421.6) mIU/L, and 1.13 (n = 12, IQR: 1.0-2.45) µg/dl which changed to 2.2 (n = 7; IQR: 0.23-3.40) mIU/L and 8.90 µg/dl (n = 8, IQR: 6.43-14.85 µg/dl), respectively at diagnosis of IIH after LT4 treatment with median daily LT4 doses of 0.89 (n = 8, IQR: 0.60 - 1.17) times the maximum recommended dose for age. To conclude, we report an adult woman with IIH following LT4 replacement for primary hypothyroidism, a rare entity. Pediatric age, prolonged symptom duration, and use of higher LT4 replacement dose may be associated with IIH following LT4 replacement.
