Weight loss and hyponatraemiaBMJ 2011; 342 doi: https://doi.org/10.1136/bmj.d405 (Published 02 March 2011) Cite this as: BMJ 2011;342:d405
- Nantia Othonos, academic foundation year 21,
- Raashda Sulaiman, specialist registrar in chemical pathology and metabolic medicine1,
- Domnick D’Costa, consultant physician, general medicine and care of the elderly2,
- Rousseau Gama, chemical pathologist and honorary professor of laboratory medicine13
- 1Department of Clinical Chemistry, New Cross Hospital, Wolverhampton, UK
- 2Department of General Medicine and Care of the Elderly, New Cross Hospital, Wolverhampton, UK
- 3Research Institute, Healthcare Sciences, Wolverhampton University, Wolverhampton, UK
- Correspondence to: N Othonos
A 60 year old South Asian woman with a one year history of lethargy and anorexia, and 3 kg weight loss was referred by her general practitioner to a medical outpatient department. Medical history included pulmonary tuberculosis, hypothyroidism, psoriasis, and Raynaud’s phenomenon. She was taking levothyroxine 100 μg daily, amlodipine 5 mg daily, and applying Polytar liquid 250 ml twice weekly to her scalp.
Clinical examination was unremarkable. Chest radiograph, abdominal ultrasound, and serum tissue transglutaminase antibodies, glucose, and thyroid function tests excluded active tuberculosis, coeliac disease, diabetes mellitus, and thyroxine overtreatment. Apart from persisting mild hyponatraemia (serum sodium concentration 128-135 mmol/L), routine haematology, biochemistry, and serum inflammatory markers were normal. The patient was not oedematous or dehydrated. Further investigations showed:
Serum sodium concentration 126 mmol/L (normal range 135-145 mmol/L)
Serum potassium concentration 4.1 mmol/L (3.5-5.0 mmol/L)
Serum urea concentration 6.9 mmol/L (1.0-7.0 mmol/L)
Serum creatinine concentration 79 μmol/L (60-120 μmol/L)
Serum glucose concentration 4.3 mmol/L (<6.1 mmol/L)
Serum osmolality 249 mmol/kg (275-295 mmol/kg)
Urine osmolality 469 mmol/kg
Urine sodium concentration 55 mmol/L
Thyroid stimulating hormone concentration 0.05 mU/L (0.27-4.20 mU/L)
Free thyroxine concentration 15.6 pmol/L (12.0-22.0 pmol/L)
Given these results, a short Synacthen test was performed using 0.25 mg Synacthen given intravenously at 0 minutes.⇓
1 What syndrome do the initial clinical findings and investigations suggest, and why was a short Synacthen test performed?
2 What diagnosis do the results of the short Synacthen test indicate, and how would you manage this condition?
3 After initiating treatment, the patient developed excessive thirst and polyuria associated with frequency and nocturia. Her plasma glucose concentration was 5.3 mmol/L. What is the significance of this?
4 What further investigations would you request?
5 In view of the new symptoms, how would you manage this patient? …