Summary

A 48-year-old Asian male, presented to the hospital for an elective total thyroidectomy in the context of 6.3 cm thyroid nodule. The fine needle aspiration cytology of the nodule confirmed papillary thyroid cancer (PTC) with some atypical histiocytes. He has a history of idiopathic arginine vasopressin deficiency (AVP-D) and has been taking oral DDAVP 100 µg daily, self-adjusting the dose based on thirst and polyuria. Additionally, he also has a history of recurrent spontaneous pneumothorax. His total thyroidectomy was aborted due to significant intraoperative bleeding, and his admission was further complicated by post-operative hyponatraemic seizure. Thyroid histology revealed the diagnosis of Langerhans cell histiocytosis (LCH), and further investigation with contrast CT demonstrated multi-organ involvement of the thyroid, lungs, and bones.

Learning points

• Langerhans cell histiocytosis (LCH) is a condition that can affect one or more organ systems, including the pituitary, where it can present as AVP deficiency. Strict monitoring of fluid balance, as well as serial monitoring of serum sodium, is essential in all patients with AVP-D in the perioperative setting.

• Iatrogenic hyponatraemic seizure is an uncommon but serious complication of DDAVP treatment in hospitalised patients with AVP-D. DDAVP dosing must be carefully monitored.

• LCH with multisystem involvement is an important mimic for metastatic conditions, and histological diagnosis is essential to guide treatment and prognosis.

• Although LCH without bone marrow involvement is unlikely to increase the risk of bleeding, its effect on tissue integrity may make surgery more challenging.

• BRAF-V600E mutation is an important driver mutation and a potential therapeutic target in the treatment of LCH.

Summary

Thyrotoxic periodic paralysis (TPP) is a rare condition characterised by acute onset hypokalaemia and paralysis which most commonly affects men of Asian descent between the ages of 20 and 40 years (1, 2). It has been reported in approximately 2% of patients with thyrotoxicosis in China and Japan (1, 2, 3). Hypokalaemia in TPP results from a massive intracellular shift of potassium induced by the thyroid hormone sensitisation of Na⁺/K⁺-ATPase (4). Treatment of TPP includes prevention of this shift by using beta-blockade, rapid potassium replacement and treatment of the underlying hyperthyroidism. We present two cases of TPP with differing outcomes. In the first case, a 33-year-old Filipino gentleman presented to our emergency department (ED) with a 3-month history of recurrent proximal lower limb weakness. Serum potassium was 2.2 mmol/L (3.3–5.1) and he was given i.v. potassium replacement. Thyroid function tests (TFTs) and thyroid antibodies were consistent with Graves thyrotoxicosis. He was discharged home on carbimazole and remains well controlled on long-term medical therapy. In the second case, a 22-year-old Malaysian gentleman presented to our ED with new-onset bilateral lower limb painless paralysis. Serum potassium was 1.9 mmol/L with TFTs demonstrating Graves thyrotoxicosis. He was treated with i.v. potassium replacement and discharged home on carbimazole and propranolol. He represented to the hospital on two further occasions with TPP and was advised to consider total thyroidectomy given his refractory Graves’ disease. These cases highlight the importance of prompt recognition of this rare life-threatening complication of Graves’ disease, especially in patients of Asian descent.

Learning points

• Thyrotoxic periodic paralysis is a rare condition characterised by hypokalaemia and acute painless muscle weakness in the presence of thyrotoxicosis.

• The signs and symptoms of thyrotoxicosis can be subtle in these patients.

• It is most commonly seen in Asian males between the ages of 20 and 40 and is most frequently caused by Graves’ disease.

• Prompt recognition is essential as it is a life-threatening condition.

• Urgent i.v. potassium replacement and beta-blockade with a non-selective beta-blocker are the mainstays of treatment.

• i.v. potassium replacement should not be given in dextrose as this can potentiate hypokalaemia.

Summary

Occasionally, autoimmune disorders can come in twos. This double trouble creates unique challenges. Myasthenia gravis co-existing with autoimmune thyroid disease occurs in only about 0.14–0.2% of cases. The patient is a 27-year-old man with a 2-month history of bilateral ptosis, diplopia, with episodes of easy fatigability, palpitations, and heat intolerance. On physical exam, the patient had an enlarged thyroid gland. Myasthenia gravis was established based on the presence of ptosis with weakness of the intraocular muscles, abnormal fatigability, and a repetitive nerve stimulation study indicated neuromuscular junction disease. Episodes of fluctuating right shoulder weakness were also noted. He was also found to have elevated FT3, FT4, and a suppressed TSH. Thyroid ultrasound revealed thyromegaly with diffused parenchymal disease. Thyroid scintigraphy showed increased uptake function at 72.4% uptake at 24 h. TRAb was positive at 4.1 U/L. Patient was started on pyridostigmine which led to a significant reduction in the frequency of ocular muscle weakness. Methimazole was also initiated. Radioactive iodine at 14.9 mci was instituted for the definitive management of hyperthyroidism. After RAI, there was abatement of the hyperthyroid symptoms, as well as improvement in the status of the myasthenia gravis, with ptosis, diplopia, and right arm weakness hardly occurring thereafter despite the reduction of the pyridostigmine dose based on a symptom diary and medication intake record. Two distinct autoimmune conditions displayed a markedly improved clinical course with the institution of radioactive iodine therapy for Graves’ disease.

Learning points

• The presence of ptosis, diplopia, and fluctuating muscle weakness are atypical in Graves’ disease and should prompt an investigation on the existence of concurrent myasthenia gravis. A prompt diagnosis of both conditions will enable the institution of appropriate management that would target both rare and challenging autoimmune diseases.

• Selecting the therapeutic options with minimal risk of morbidity and mortality, which could lead to maximal benefit especially in a resource-limited setting is paramount.

• Targeted non-surgical management can lead to the remission of two autoimmune diseases which can result in patient satisfaction and improved quality of life.

Summary

Thyroid storm is a rare but potentially life-threatening complication of excessive thyroid hormone action. It is associated with a hypercoagulable state and reported to increase the risk of thromboembolism. However, the role of anticoagulation in thyroid storm still remains controversial and inconclusive. A 22-year-old male with no significant past medical history presented with acute severe generalised abdominal pain. He was found to be profoundly thyrotoxic on arrival at our institution and subsequently diagnosed with thyroid storm secondary to newly diagnosed Graves’ disease. Extensive thromboses of the splanchnic, iliac, femoral veins and pulmonary arteries were subsequently demonstrated on CT scan. He had prolonged bowel ileus as a sequela of mesenteric ischaemia requiring total parenteral nutrition and non-oral forms of anti-thyroid drugs for management of hyperthyroidism. He was in sinus rhythm throughout his inpatient stay, and there was no personal history of prothrombotic conditions. His thrombophilia screen was normal. He eventually required jejunectomy due to jejunal ischaemia from extensive involvement of portal and mesenteric veins. He underwent radioiodine ablation for definitive treatment. He is currently hypothyroid and receiving thyroxine replacement. Thyroid storms are hypercoagulable states and can be associated with extensive thromboembolism even in the absence of atrial fibrillation. To our knowledge, this is the first report of severe extensive thromboembolism complicated by severe mesenteric ischaemia and bowel ileus in the setting of a thyroid storm. Routine prophylactic anticoagulation should be considered in those presenting with thyroid storms.

Learning points:

• Prolonged use of rectal propylthiouracil (PTU) for managing hyperthyroidism was effective in a patient who cannot take oral anti-thyroid drugs.

• Hyperthyroidism is a hypercoagulable state due to an imbalance between coagulation and fibrinolytic factors.

• Thyroid storm can be associated with extensive thromboembolism even in the absence of atrial fibrillation; routine prophylactic anticoagulation should be considered in the setting of thyroid storms.

Learning points:

• Even in white patients, DKA is not synonymous with type 1 diabetes and autoimmune beta cell failure. KPD needs to be considered in all patients presenting with DKA, even though it will not influence their initial treatment.

• Aside from markers of endogenous beta cell function and islet autoimmunity, which in any case are unlikely to be immediately available to clinicians, consideration of family history of type 2 diabetes and cutaneous markers of insulin resistance might help to identify those with KPD and are more readily apparent in the acute setting, though not emphasised in guidelines.

• Consideration of KPD should never alter the management of the acute severe metabolic derangement of DKA, and phasing out of insulin therapy requires frequent attendance and meticulous and cautious surveillance by a team of experienced diabetes care providers.

Learning points:

• Tolvaptan can be used in paediatric patients with SIADH to allow hyperhydration during chemotherapy.

• Tolvaptan has profound effects on urinary output and meticulous monitoring of fluid balance and sodium 
levels is therefore warranted.

• Tolvaptan was well tolerated without significant side effects.