Comment

Autoimmune thyroiditis (which, if associated with a goitre, is called Hashimoto disease) is a chronic inflammatory disorder of the thyroid gland with lymphocytic and cytokine-mediated thyroid destruction. Thyroglobulin autoantibodies/thyroid peroxidise autoantibodies are present in 95% of cases of autoimmune thyroiditis. It affects female patients more than male patients, and this ratio difference increases with age. Autoimmune thyroiditis is more common in conditions associated with abnormal karyotype such as Turner's, Klinefelter's and Down's syndrome and as part of other autoimmune diseases.2 3 It usually results in hypothyroidism requiring replacement therapy with levothyroxine, although patients can remain euthyroid and need regular monitoring of their thyroid function.

Following her initial diagnosis, Emily started to develop panic attacks which were centred around eating. She had never eaten breakfast and became self-conscious about eating in school in front of her peers, so she began skipping lunch. This resulted in her eating only one meal a day. She began to lose weight. Over the following 4 months, she found school increasingly difficult and stressful. Four months after her initial presentation, she stopped attending school altogether because of anxiety and panic attacks. Her parents became increasingly concerned by her weight loss and her worsening anxiety. She was referred to a child and adolescent psychiatrist for review.

Eleven months after her initial presentation, Emily now weighed 40 kg (0.4th centile) and her height 165 cm (50–75th centile), giving her a BMI of 14.6 kg/m². She was biochemically euthyroid throughout – TSH 0.7 mIU/l (0.4–4.0), fT4 22.9 pmol/l (10.3–24.5). Emily was very needle phobic and would not eat at all for days before her blood test, so these were kept to a minimum.

A joint decision was reached with Emily's parents, paediatrician and psychiatric consultants that the most likely diagnosis was anorexia nervosa and that she would require admission to a specialist eating disorder centre.

Emily was admitted to a specialist eating disorder centre as an inpatient. She was diagnosed as having some body image distortion in keeping with a diagnosis of anorexia nervosa. However, it was also noted that she had some atypical features such as extreme anxiety with panic attacks on eating and absence of “fat phobia”; the food choices she made were not generally low in fat.

Comment

Anorexia nervosa is a psychiatric disorder characterised by a deliberate and extreme loss of weight, body image distortion and morbid fear of weight gain.4,–,7 Weight is obsessively controlled by means of deliberate starvation, excessive exercising, vomiting/purging and laxative, diuretic and diet pill abuse. Higher rates of childhood onset obsessive–compulsive disorder and social phobia are associated with anorexia nervosa.4 There is a female preponderance with only 10% of cases of anorexia seen in males. The incidence of anorexia nervosa is increasing, and it appears to be affecting children at younger ages, where there is a more equal sex ratio. The prevalence in the UK is thought to be approximately 1% in women aged 15–30 years old. Mortality from anorexia is 20% and results from suicide and complications of starvation (table 1).5

Management involves an individualised program usually in the outpatient but occasionally in the inpatient setting. The aim is to restore weight by approximately 0.5–1 kg/week. It generally combines nutritional rehabilitation, medical intervention, psychotherapeutic treatment, psychosocial rehabilitation and family therapies. Close monitoring during commencement of re-feeding is required as re-feeding syndrome can develop which can be fatal. This involves close monitoring of vital signs and blood tests to monitor electrolytes, phosphate, magnesium and glucose (table 2).4

Emily's initial examination found her to be hypotensive, BP 80/60 mm Hg, tachycardic, HR 105 bpm with cool peripheries and an axillary temperature, 35.4°C.

Bloods:

Emily was commenced on a weight restoration programme which consisted of hydrating her with 2 litres per day of fluid orally. Gradual increase in daily calorie intake from 400 to 2000 kcal. All inpatients were kept on a salt-restrictive diet.

Emily continued on levothyroxine 100 µg and was commenced on multivitamin tablets and in light of her anaemia was also commenced on ferrous sulphate 200 mg three times daily.

Three weeks after admission, Emily began to deteriorate. Her panic attacks appeared to worsen and were associated with hyperventilation. Her BP dropped further to 67/50 mm Hg, HR 124 bpm. She had abdominal pain, headaches, nausea, feeling faint and vomited twice. She was brought by ambulance to accident and emergency.

On arrival at accident and emergency, she was found to have a BP of 94/60 mm Hg, HR 80 bpm, RR 16 bpm, Sats 100% air and was afebrile.

On examination, she was noted to be emaciated but alert and orientated with a Glasgow Coma Scale of 15/15.

She was well perfused with a capillary refill of <2 s and had normal cardiovascular, respiratory and abdominal examination. She denied any abdominal tenderness during her examination (fig 1).

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Figure 1

(A) Photo of Emily a year before the admission to hospital and (B) during hospital admission.

Routine bloods were taken and shown:

She was given a provisional diagnosis of symptomatic hyponatraemia secondary to drinking large volumes of water while on a no-salt diet. She denied diuretic and laxative abuse. The possibility of adreno-cortical insufficiency was also considered.

Emily was known to suffer from anorexia nervosa, and so, it was not unexpected that she should be underweight, hypothermic, hypotensive with hyponatraemia as this would all be compatible with her diagnosis. The hyperkaelaemia could be put down to blood sampling difficulties in a peripherally shut down anorexic patient causing haemolysis and raised potassium levels. Many people with hypotension especially if they have postural hypotension can feel nauseated and dizzy on standing up.

Comment

Hyponatraemia is a common biochemical abnormality and can be divided into four main categories: (1) sodium loss, (2) dilutional effect (water excess), (3) inappropriate antidiuretic hormone (ADH) secretion and (4) pseudo-hyponatraemia due to displacement of sodium to the aqueous phase but still being measured as part of the total volume of plasma. This can occur in states of hyperglycaemia/hyperlipidaemia or hyperproteinaemias. The actual plasma osmolarity of sodium is actually within normal levels and, hence, does not require correcting but should be calculated using specific formulae to ensure this (table 3).

Emily was put onto a strict input/output fluid and food chart and was restricted to 500 ml of fluid overnight and was encouraged to have salty foods, which she admitted she had been craving.

Her morning bloods showed:

Her levothyroxine was decreased to 75 µg, and in light of a low random cortisol level, a synacthen test was performed (table 4).

On closer inspection postsynacthen test, it was noticed that Emily had increased pigmentation of her knees, knuckles and hands (fig 2).

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Figure 2

(A–C) Hyperpigmentation of Emily's knuckles (A) and knees (B and C).

Emily was diagnosed with Addison's disease and was commenced on replacement doses of hydrocortisone: 10 mg morning, 5 mg afternoon and 5 mg evening.

Emily's BP remained low at 84/48 mm Hg, HR 85 bpm. She was retching, had vomited once and had epigastric abdominal pain. She was unable to eat or drink, as she felt very unwell and her fluid input had been minimal.

Emily was commenced on intravenous hydrocortisone, given three boluses of 0.9% sodium chloride 10 ml/kg and commenced on maintenance intravenous fluid 0.9% sodium chloride.

On review, Emily's BP improved to 109/67 mm Hg, HR 110 bpm. Repeat bloods showed a gradual increase of her sodium over the accompanying days. She was commenced on oral fludrocortisone following her adrenal crisis and was put back onto oral hydrocortisone once she returned to haemodynamic stability.

Over the next few weeks, the following results came back which confirmed the diagnosis of Addison's disease.

Comment

Addison's disease is a relatively rare disorder with an estimated prevalence of 120/million population; it is even rarer in the paediatric population.3 8,–,10 Addison's disease is primary adrenal failure. Autoimmune adrenitis is the most common cause of primary adrenal insufficiency post-infancy. In the UK, it accounts for 70–90% of cases. There may be positive adrenal antibodies present. Lymphocytic infiltrate cause destruction of the adrenal cortex, leading to failure of cortisol, aldosterone and adrenal androgen production. Cortisol levels are decreased with loss of circadian pattern associated with a persistent elevated ACTH level (Emily's ACTH levels were very elevated at 1918 ng/l). ACTH has an affinity for melanocortin-1 receptor; thus, excess of ACTH results in hyperpigmentation. Symptoms include lethargy, weight loss, gastrointestinal complaints (anorexia, nausea, vomiting and diarrhoea), increasing skin pigmentation especially in the skin creases, old scars and buccal mucosa and salt craving. Due to the slow progression of the disease, diagnosis is often delayed, and it may only be diagnosed during an Addisonian crisis when demand for cortisol cannot be met by the failing adrenal gland. Therefore, an appropriate stress response cannot be elicited leading to vomiting, drowsiness, hypotension, hyponatraemia, hyperkalaemia, hypoglycaemia and eventually collapse and coma. Diagnosis can be confirmed by an elevated level of ACTH and lack of increase of cortisol in response to synacthen test. Renin levels are high with a low/undetectable aldosterone levels as seen with Emily. Fasting glucose is low/normal.