Palpitations in a young patient: are we always sure about the diagnosis?

Sir, Palpitations remain one of the commonest presentations in patients in an acute medical setup. It is an established symptom in patients who are older and have evidence of structural heart damage consequent to previous ischaemic heart disease, heart failure or defects involving the cardiac muscles or valves. It is also very commonly encountered in people with infections, metabolic derangements or often due to idiopathic reasons when a definitive cause is not established after multiple investigations. The situation becomes slightly more tricky and challenging when patients are young and present to the emergency department with recurrent attacks of palpitations for no apparent cause. Clinicians have to keep an open mind in observing these patients and investigate them appropriately to get to the bottom of the real problem. We present an interesting case of a young patient with palpitations who posed a real diagnostic challenge. A 25-year-old female veterinary nurse was admitted to the acute medical unit with symptoms of palpitations which were present for 2 months. Her symptoms were intermittent, short lasting, self resolving and was not related to any exertion. She also had accompanying breathlessness during these episodes and complained of mild tiredness. There was no history of weight loss, change in appetite, sweating, tremors, bowel or menstrual abnormalities, mood swings, weather preferences or pedal swelling. She was under some stress relating to her family and personal circumstances. Her past medical history included Crohn’s disease and probable bulimia. She was a non-smoker and did not have any addiction to alcohol. She had a few relatives who had thyroid problems but was unsure about their biochemical status. Enquiring further into her history, we learned that she was recently reviewed in the cardiology outpatient department following a referral from her general practitioner (GP) to whom she presented earlier with similar complaints of palpitation. She went on to have an echocardiogram, ECG and two samples (24 h collection) of urine for catecholamine’s which were all within normal limits. Interestingly, a thyroid function was not performed at that time as she did not have any dysthyroid features. It was felt that her palpitations could be well related to her stress and anxiety state but a provisional diagnosis of ‘idiopathic sinus tachycardia’ was made and she was commenced on a β blocker (metoprolol) which she took for a few days but discontinued later after she felt symptomatically better. On her present admission, she was noted to be anxious with a low body mass index of 20 kg/m2. There was evidence of mild tremulousness of her upper extremities but there was no palpable thyroid swelling or evidence of thyroid orbitopathy. She was found to be tachycardic (heart rate between 100–120/min) but her blood pressure and heart sounds were within normal limits. Her investigations showed a normal full blood count, urea and electrolytes and liver function tests but her corrected calcium was found to be high (2.86 mmol/l). Her thyroid functions were abnormal as her serum thyrotropin (TSH) was suppressed at <0.01 mU/l and her free thyroxine (FT4) and free tri-iodothyronine (FT3) were elevated and recorded to be >77 pmol/l and >46 pmol/l respectively. A probable diagnosis of Grave’s disease was made and she was commenced on carbimazole 30 mg once daily with a β blocker (propranolol) for using it during periods of palpitation. She was discharged home after her palpitations settled and an outpatient endocrinology follow up was made. She was seen in the clinic in the next 2 months but was found to have no symptomatic improvement as her palpitations persisted. She had lost some weight by then (>5 kg) and her symptoms of tiredness got worse. Biochemically, her thyroid function tests (TFT’s) remained unchanged (suppressed TSH and elevated FT4 and FT3) although she did admit that she has missed her tablets on innumerable occasions. She had some counselling and was encouraged to take her tablets on a regular basis. Her anti-thyro-peroxidase antibody and TSH receptor antibody were within normal limits. She was followed up again in the next few weeks but her clinical and biochemical picture remained identical to her previous visits. The carbimazole dose was increased to 60 mg and she was called back again in 6 weeks time with repeat thyroid function test. Her next visit did not yield any change in her symptoms and further investigations were arranged. Her TFT’s remained deranged with a TSH of <0.01 mU/l and her free hormones showed an FT4 of >77 pmol/l and an FT3 of >46 pmol/l. Her serum thyroglobulin was low normal (5 ng/ml) and a thyroid ultrasound showed normal size and echo texture of the gland. Her corrected calcium at that point was marginally better (2.6 mmol/l) but her serum parathormone was within normal limits. A technetium thyroid uptake scan was organized which only showed an uptake of 0.1% and was interpreted as negative. Her symptoms were florid at that point and a decision was made to admit her electively to hospital to improve her medically. The aim was to enable her to take her carbimazole tablets under medical supervision and observe for any differences in her clinical or biochemical profile. Her only major clinical symptom at the point was palpitation although there were accompanying symptoms of weight loss, tiredness and mild breathlessness. Her thyroid biochemistry never settled but we felt there was a fair degree of disparity between her clinical illness and the biochemical picture. We arranged for a faecal thyroxine estimation which showed an elevated concentration of thyroxine (T4). This led us to the belief that her symptoms and her thyroid biochemistry were not likely due to endogenous or intrinsic thyroid disease but due to surreptitious use of the product from outside. The points in favour of a diagnosis was that her TFT’s never settled with treatment (TSH persistently <0.01 mU/l and FT4 > 77 pmol/l and FT3 > 46 pmol/l) and her serum thyroglobulin was low. Moreover, she also had a negative antibody status and her ultrasound and technetium uptake scan were all normal. We decided to confront her with the possible diagnosis of ‘thyrotoxicosis factitia’ in our minds. She was shocked at the beginning but became tearful and submissive after a brief period into the interview. She confirmed that she was using some herbal supplements for losing weight for the past few months but did not disclose the source from where she used to receive them. She agreed not to take those supplements further and a psychiatry counselling was arranged. Her carbimazole was stopped but her β blocker was continued for symptomatic improvement. Unfortunately, she got pre-occupied with the thoughts that her surreptitious use of herbal medicines which possibly contained thyroxine extracts was discovered and chose to self discharge from the hospital. She was given a few follow-up appointments in the endocrine clinic which she never attended. This case strongly proves the strong and strange obsession of the young generation to lose weight and the extreme measures adopted to pursue this unrealistic goal. Our patient was a veterinary nurse, had a history of bulimia and had relatives who were possibly on thyroxine. She was well placed to have an access to either a veterinary thyroxine preparation or from her own relatives. We could not confirm or validate her intake of herbal medicines for losing weight as she did not disclose the name of the person who prescribed or dispensed it to her. ‘Factitious thyrotoxicosis’ is produced due to ingestion of excessive thyroid hormones from an exogenous source. This condition is commonly noted in people who have relatives who suffer from thyroid conditions and have access to thyroxine preparations due to their profession. Diagnosing this condition can be difficult and requires a high index of suspicion without which misdiagnoses and mismanagement are common. This condition is not commonly encountered but treatment for weight loss, depression, infertility, menstrual abnormalities and attempted shrinkage of colloid goitre in patients with normal function are some of the reasons that are commonly attributable for the surreptitious use of thyroxine.1 Cosmetic creams containing thyroid or iodine preparations and weight reducing herbal medicines has been also considered to be common offenders.2 The diagnosis of factitious thyrotoxicosis should be suspected in any patient with apparent hyperthyroidism but lacking thyroid enlargement. Patients usually lack clinical signs of Graves’s disease or signs of acute or sub acute thyroiditis.2 It is predominantly encountered in young or middle age females with psychopathological conditions but should be also suspected in old people when thyrotoxicosis is inexplicable in origin.3 The systemic effects of prolonged exogenous thyroxine intake have been well reported. Hypercalcaemia in any form can feature due to the direct effects of thyroid hormones on the bone leading to increased osteoclastic activity.4 Reports have also confirmed occurrence of hypokalaemic periodic paralysis5 and acute myocardial infarction6 in patients with factitious thyrotoxicosis. Prolonged intake of thyroxine can also precipitate a thyroid storm which is often technically difficult to manage.7 Diagnosis is based on a clinical suspicion, a proper medication history and physical examination in different patient groups. Patients usually have thyrotoxic biochemistry and a low uptake of radioiodine. Colour flow doppler shows almost absent blood flow to the thyroid.8 Thyroid antibodies are negative and serum thyroglobulin is usually low or undetectable.9 Another important diagnostic tool is the estimation of 24 h urine iodine concentration and measurement of faecal thyroxine. Faecal T4 which are ∼1 nmol/kg in normal healthy subjects and mildly increased in Graves’s disease is markedly elevated in people with thyrotoxicosis factitia.10 In general, patients often present to GP’s or to the acute medical units with non-specific and vague symptoms of palpitations and tiredness. They often tend to deny surreptitious use of thyroxine extracts from other sources and confirming a diagnosis then becomes very difficult. Physicians dealing with them should have an open mind while exploring differential diagnoses of palpitations in young people when the diagnosis is not apparent. Symptoms usually subside after discontinuation of thyroxine intake but a careful and sensitive enquiry in the early part of the disease often gives a clue to the diagnosis. Most of the patients should be referred to a psychiatrist as they have underlying psychopathological conditions that need to be explored by experts.