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LETTER TO EDITOR
Year : 2015  |  Volume : 4  |  Issue : 1  |  Page : 46-47

Unusual etiology of secondary thyrotoxicosis and its presentation


Department of Medical Oncology, M S Ramaiah Medical College, MSRIT Post, Bangalore, Karnataka, India

Date of Web Publication23-Jan-2015

Correspondence Address:
Vinayak V Maka
Department of Medical Oncology, M S Ramaiah Medical College, MSRIT Post, Bangalore, Karnataka
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/2278-330X.149954

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How to cite this article:
Maka VV, Murali S, Kilara N. Unusual etiology of secondary thyrotoxicosis and its presentation. South Asian J Cancer 2015;4:46-7

How to cite this URL:
Maka VV, Murali S, Kilara N. Unusual etiology of secondary thyrotoxicosis and its presentation. South Asian J Cancer [serial online] 2015 [cited 2019 Sep 15];4:46-7. Available from: http://journal.sajc.org/text.asp?2015/4/1/46/149954

Dear Editor,

The incidence of clinical hyperthyroidism has been reported as 0.8/1,000 women per year, and it is less common in men. [1] Causes of thyrotoxicosis include Grave's disease, toxic multinodular goiter, toxic adenoma, and thyroiditis. Rarely, thyrotoxicosis can arise as a paraneoplastic syndrome. In this setting, systemic symptoms of underlying malignancy may be wrongly attributed to primary hyperthyroidism leading to a delay in diagnosis. [2] We report a rare case of thyrotoxicosis due to metastatic nonseminomatous germ cell tumor (NSGCT) of testis that highlights the importance of a systematic clinical and biochemical assessment.

A 48-year-old man presented with persistent gradual back pain for 2 months with inconclusive magnetic resonance imaging (MRI) findings, so lumbar spondylitis was assumed and started on symptomatic treatment. On laboratory results, patient showing primary hyperthyroidism (triiodothyronine (T3) 14.2 ng/dL, thyroxin (T4) 138 μg/dL, and thyroid stimulating hormone (TSH) 0.14 μIU/mL) was treated with radioiodine thyroid ablation in absence of hyperthyroidism signs and symptoms based upon enhanced diffuse thyroid tracer uptake on thyroid scan mimicking Grave's disease.

On appearance of palpable supraclavicular lymph node, palpable mass in the left upper abdominal quadrant and enlarged right side testis with secondary hydrocele were detected on systemic examination, which were probably missed on initial evaluation. Fine needle aspiration cytology of supraclavicular lymph node showed a germ cell tumor. Human chorionic gonadotropin (HCG; 57,220 mIU/L), alfa fetoprotein (193 U/L), and lactate dehydrogenase (777 U/L) were markedly elevated. Final diagnosis of carcinoma testis, NSGCT, stage III C, poor prognosis risk group with paraneoplastic hyperthyroidism was arrived upon and started upon two cycles of PEB (cisplatin, etoposide, bleomycin) chemotherapy. Patient underwent high inguinal right side orchiectomy after two cycles of PEB chemotherapy, and on histopathological examination, presence of mixed germ cell tumor with predominantly teratoma (90%) and choriocarcinoma (5%) elements was diagnosed. His tumor marker values were decreased on chemotherapy with recovery of thyroid function with thyroxin supplementation [Table 1]. Two more cycles of PEB chemotherapy with surgical excision of residual disease was planned.
Table 1: Serial tumor markers showing progressive decline in their levels in response to chemotherapy and orchiectomy

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Paraneoplastic hyperthyroidism is a rare but recognized phenomenon associated with NSGCT and high-serum HCG levels, although the exact prevalence is unknown. In one large prospective cohort analysis study of 144 patients, Oosting et al., reported hyperthyroidism to be present in 3.5% of the patients with disseminated NSGCT and almost 50% in patients with high-serum HCG levels (>50,000 IU/L). [3] Exceedingly high concentration of HCG in occasional germ cell tumors can overcome its low-binding affinity of the alpha subunit for TSH receptor for inducing secondary hyperthyroidism. There is lag time between elevated thyroid hormone levels and clinical evidence of hyperthyroidism. [4] Despite lack of standard guidelines for management of paraneoplastic hyperthyroidism, symptomatic hyperthyroidism should be treated immediately with β-adrenergic receptor antagonist and antithyroid drugs for better tolerability of chemotherapy. [3],[5],[6] The treatment of the underlying cancer is definitive treatment of paraneoplastic hyperthyroidism. In conclusion, this case highlights the importance of a comprehensive clinical history and systematic physical examination including genitals for all patients presenting with hyperthyroidism.


  Acknowledgments Top


Nalini Kilara has revised the manuscript critically and gave final approval of the version to be published.


  Consent Top


Written informed consent was obtained from the subject for publishing this case report and accompanying images.

 
  References Top

1.
Vanderpump MP, Tunbridge WM, French JM, Appleton D, Bates D, Clark F, et al. The incidence of thyroid disorder in the community: A twenty-year follow-up of the Whickham Survey. Clin Endocrinol (Oxf) 1995;43:55-68.  Back to cited text no. 1
    
2.
McCracken EJ, Johnston PC, Lindsay JR, Mulholland C, McAleer JJ, Black RN. Testicular choriocarcinoma: An unusual case of paraneoplastic thyrotoxicosis. QJM 2012;105:675-7.  Back to cited text no. 2
    
3.
Oosting SF, de Haas EC, Links TP, de Bruin D, Sluiter WJ, de Jong IJ, et al. Prevalence of paraneoplastic hyperthyroidism in patients with metastatic non-seminomatous germ-cell tumours. Ann Oncol 2010;21:104-8.  Back to cited text no. 3
    
4.
Oppenheimer JH. Thyroid hormone action at the nuclear level. Ann Intern Med 1985;102:374-84.  Back to cited text no. 4
    
5.
Kellner O, Voigt W, Schneyer U, Dempke W, Schmoll HJ. HCG induced hyperthyreosis in germ cell cancer. Anticancer Res 2000;20:5135-8.  Back to cited text no. 5
    
6.
Meister LH, Hauck PR, Graf H, Carvalho GA. Hyperthyroidism due to secretion of human chorionic gonadotropin in a patient with metastatic choriocarcinoma. Arq Bras Endocrinol Metabol 2005;49:319-22.  Back to cited text no. 6
    



 
 
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