Atypical presentation of thyroid storm: a diagnostic dilemma

Abstract

Thyroid storm (accelerated hyperthyroidism) is an uncommon life-threatening emergency. The diagnosis is difficult and at times delayed owing to atypical presentation. Early diagnosis is the key to its successful management. We came across a patient who had presentations of acute abdomen but later diagnosed in thyroid storm. Multiorgan involvement leads all resuscitative measures futile and prevented us to salvage the patient.

Background

Thyroid storm is a rare medical emergency with an incidence of 0.2 cases per 100 000 population.¹ There is exacerbation of hyperthyroid state leading to decompensation of various system.² The presentation may be non-specific, causing difficulty in diagnosis. The delay in treatment is fatal since the condition carries high mortality rate.³ We hereby report an undiagnosed case of hyperthyroidism who presented with atypical features of multiple organ involvement and eventually diagnosed in thyroid crisis along with hypomagnesaemia.

Case presentation

A 45-year-old thin built female farm labourer presented to the emergency department (ED) with the history of severe abdominal pain along with repeated nausea and vomiting since last 12 hours, but there was no history of diarrhoea or loose motions. Intermittent pain in abdomen was present for the last 10 days and pedal oedema for the last 5 days. She was a chronic smoker with no recent history of drug intake or abuse. Past and family history were non-contributory. Recent history of weight loss or fever was absent. Vital signs were pulse rate (PR) 130 beats/min (regular, low volume), blood pressure (BP) 90/60 mm Hg, normothermic, vesicular breath sounds and bowel sounds absent with no hepatosplenomegaly.

Investigations

Investigations revealed haemoglobin 10.2 g/L (13.8–17.5 g/L); total leucocyte count 16×10⁹/L; differential leucocyte count neutrophil 64%, lymphocyte 28%, monocyte 7%; platelet count 140×10⁹/L(150-400×10⁹/L); blood urea 91 mg/dl (10–50 mg/dl); serum creatinine 0.8 mg/dl (0.5–1.8 mg/dl); serum bilirubin 6 mg/dl (0.8–1 mg/dl); serum glutamic-oxaloacetic transaminase 80 IU/L (upto 50 IU/L); serum glutamic pyruvic transaminase 68 IU/L (upto 50 IU/L); serum protein 8 g/dl (6.6–8.7g/dl); prothrombin time/international normalised ratio (INR) 61/6.49; serum sodium 136 mE/L (130–149 mE/L) and serum potassium 4.8 mE/L (3.5–5 mE/L); blood sugar was 60 mg/dL (70–130 mg/dL). Chest X-ray was clear with no free gas under diaphragm. Focused abdominal sonography for trauma was negative for free fluid.

Differential diagnosis

On prima facies, she was a case of intestinal pathology (gut infection, obstruction or perforation).

Treatment

Conservative management was done with injection ranitidine, injection hyoscine butylbromide and injection ondansetron. As blood sugar was 60 mg/dL, 30 mL of 50% dextrose was given followed by 100 mL/hour dextrose normal saline.

Outcome and follow-up

After 4 hours of observation in the ED, patient got anxious, restless and complained of palpitation and shortness of breath. Vitals recorded were BP 110/72 mm Hg, PR 170 beats/min, SpO₂ 86% (on room air) and 12-lead ECG showed atrial fibrillation with fast ventricular response. ABG obtained on room air showed pH 06.95; PaCO₂ 46 mm Hg; PaO₂ 77 mm Hg; bicarbonate 12 mmol/L; sodium 135 mmol/L, potassium 3.5 mmol/L, calcium 0.74 mmol/L, lactate 4.8 mmol/L and blood sugar 60 mg/dL. Diltiazem 12.5 mg administered intravenously. Heart rate (HR) settled to 130 beats/min and was regular after 10 min, BP 102/64 mm Hg, SpO₂ 94% (on Venti mask 5 L/min). Hundred millilitres of sodium bicarbonate was infused. But as her Glassgow Coma Scale gradually declined to 9/15 (E₂V₂M₄), she was immediately intubated. While intubation, a swelling of size 2×3 cm in front of her neck was noticed. Patient was shifted to the intensive care unit (ICU) for further management and elective ventilation. On detailed examination, she was afebrile with muddy sclera and bilateral pedal oedema. In view of the swelling in neck, urgent thyroid profile was sent, and ultrasound of neck revealed thyroid nodule with heterogeneous appearance along with increased blood flow in colour doppler. Patient was not fluid responsive (inferior vena caval distensibility index variations <12%) with BP 90/40 mm Hg and HR 70 beats/min. Norepinephrine infusion at 6 µg/min (titrated) and followed by 10 mg/hour infusion was started. This patient met the Burch and Wartofsky classification⁴ for thyroid storm on presentation in the ICU (score of 85: 20 for unexplained jaundice, 20 for tachycardia, 5 for pedal oedema, 10 for atrial fibrillation, 20 for moderate mental status alteration and 10 for precipitant history). Thyroid profile revealed TSH <0.00005 µIU/mL (0.35–5.5 µIU/mL), T4 150.69 nmol/L (57–148 nmol/L) and T3 4.20 nmol/L (1.54–3.08 nmol/L). Patient was diagnosed to be in thyroid crisis along with hypoglycaemia and hyperbilirubinaemia. Tablet methimazole 20 mg was given through Ryle’s tube. Tablet propranolol was withheld as HR was 60 beats/min, and BP was 86/40 mm Hg. Intravenous dexamethasone 8 mg given followed by 4 mg 6 hourly. Transthoracic echocardiography revealed cardiac out 2.6 L/min, ejection fraction 35% and stroke volume 30 mL along with enlarged left ventricle with fractional shortening of less than 25%. Dobutamine infusion started at 10 µg/kg/min but increased to 20 µg/kg/min as vitals deteriorated gradually. Patient suddenly developed an event of torsades de pointes (figure 1). Serum magnesium levels done immediately revealed 0.7 mmol/L. To correct hypomagnesaemia injection Magnesium sulfate (MgSO₄) 2 g (16 mEq) was given over 5 min followed by 5 g in 500 mL isotonic saline over the next 6 hours. Patient succumbed to death around 8 hours after admission to the ICU.

Figure 1.

12-lead ECG showing torsades de pointes.

Discussion

Incidence of thyroid storm is about 10% in hospital admissions with thyrotoxicosis, and male-to-female ratio is 1:10.⁵ This fulminating condition carries a mortality of 20%–30%.² Though the pathophysiology of thyroid storm is unclear, the hypothesis suggested is an increase in free T₃ concentrations and increase in β-adrenergic receptor activation.⁶ In undiagnosed patients, thyrotoxic crisis often occurs in the presence of its triggers like infection, surgery, hypoglycaemia, pregnancy and delivery, adrenocortical insufficiency, diabetic ketoacidosis, severe emotional stress and strenuous exercise. The diagnosis of thyroid storm is difficult since it may mimic sepsis, heat stroke, gastrointestinal infection or ischaemic heart disease especially in undiagnosed thyrotoxic patient.⁷

Our patient was normothermic and had features suggestive of gut pathology. Jha et al reported a thyrotoxic patient who presented with abdominal pain, but their patient was a known case of hyperthyroidism.⁸ There are reports of patients presenting as acute abdomen and undergoing laparotomy, which ultimately had negative finding. Later, the patients were diagnosed in thyroid storm.² In our case, gut infection was most likely cause of precipitation of thyroid storm. Another important finding was atrial fibrillation. There was no medical history suggestive of myocardial infarction, dysrhythmias, coronary artery disease or heart failure. Martinez-Diaz et al also reported atrial fibrillation from thyroid storm in a previously undiagnosed patient. Atrial fibrillation occurs in 10%–20% of patients with hyperthyroidism.⁹ Burch and Wartofsky score⁴ of 85 was suggestive of thyroid storm, which was later confirmed by thyroid function tests. A small neck swelling, which was noticed at the time of intubation, raised the suspicion of thyroid storm.

The treatment of thyroid storm requires multifaceted approach with hydration, cooling, beta-receptor antagonists, ionotrope support, glucocorticoids and specific antithyroid drugs to decrease the synthesis of thyroid hormones and their circulating levels.¹⁰ The treatment of aggravating factor is of paramount importance.¹¹ The standard management protocol was followed in our case. Generally, it is recommended that propylthiouracil (PTU) is preferred over methimazole for the acute treatment of life-threatening thyroid storm in an ICU setting as it blocks T4-to-T3 conversion, and T3 levels drop by approximately 45% within 24 hours after PTU, but only 10%–15% within 24 hours after methimazole.^{12 13} In our case, we used methimazole as PTU was not available in our hospital. But I would like to highlight that in Japan, methimazole is preferred over PTU, and in a retrospective study of 356 patients, there was no difference in mortality or disease severity in patients receiving methimazole or PTU.^{14 15} In our case, we could not give iodine solution after the diagnosis, especially after methimazole administration, because iodine can rapidly block new hormone synthesis and release.¹⁶ Moreover, the patient had multiorgan involvement. There was persistent hypoglycaemia with unexplained jaundice, deranged liver function test and increased INR, all indicating a very poor prognosis in thyrotoxicosis patient.¹⁷ Cardiac decompensation was not responsive to any treatment. The serum magnesium levels were low, leading to torsade de pointes. Hypomagnesaemia in a hyperthyroid patient leading to torsa de pointes is quite uncommon finding not yet reported in the literature.

Learning points.

• Thyroid storm is an alarming endocrine emergency.

• The confirmation of the diagnosis may be difficult or delayed due to uncommon presentations.

• Burch-Wartofsky Point Scale ≥45 is highly suggestive of thyroid storm independent of thyroid hormone levels.

• Persistent hypoglycaemia along with unexplained jaundice and deranged coagulation profile indicates a very poor prognosis in thyrotoxicosis patient.

• Hypomagnesaemia further complicates the clinical scenario.

• High index of suspicion and institution of immediate drug therapy may limit the morbidity and mortality.