B.A.M. is an 88-year-old man who was admitted to the Internal Medicine Department after being referred to the Accident and Emergency Department from the day centre he attends daily, for an episode of disconnection from his environment. The patient has been widowed for seven years, lives at home with a carer and has good social and family support.
He is on regular treatment with: atenolol (25 mg/day), acetylsalicylic acid (300 mg/day), omeprazole (40 mg/day), nitroglycerin (patch, 5 mg/day), simvastatin (20 mg/day), enalapril (20 mg)/hydrochlorothiazide (12,5 mg) 1-0-½, tamsulosin (0.4mg/day), levothyroxine (50 mcg-75 mcg-0), bromazepam (1.5 mg/night), sertraline (50 mg/day from the previous day, previously 25 mg/day).
His personal history includes the following: High blood pressure under treatment. Ischaemic heart disease (AMI in 1995). Peripheral arteriopathy in follow-up for vascular surgery. Prostatism with high-stable PSA. Hypothyroidism in substitutive treatment. Long-standing depressive syndrome, treated for 10 years with benzodiazepines and different antidepressants, always by her primary care physician (MAP). No other psychiatric history. The patient has had two previous admissions:
One admission three years ago to the Internal Medicine service for hyponatraemia (plasma Na 116 mEq/l) which was accompanied by functional deterioration. The family reported an abrupt worsening of the patient since two days before admission, with urinary incontinence, partial disorientation in time and space, and also associated a presumed worsening of the patient's depressive symptoms with the initiation of sertraline (75mg/day) 13 days earlier (depressed mood, feeling of imminent death, nocturnal agitation). Water restriction was carried out and treatment with the diuretic hydrochlorothiazide (50 mg/day) and the newly introduced sertraline (75 mg/day) was discontinued. He was discharged with a blood Na of 127 mEq/l. The main diagnosis at discharge was "Hyponatraemia probably due to diuretics".
A second admission 20 months ago to the Neurology Department after presenting to the Emergency Department of the hospital reporting a feeling of dizziness with spinning of objects in the home, without nausea or vomiting, with a feeling of malaise and a sensation of weakness in the lower limbs. The patient was not being treated with any diuretic, and 15 days prior to admission he had been reintroduced antidepressant medication in his usual treatment (citalopram 30 mg/day) due to worsening of his depressive symptoms. He was admitted with a plasma Na of 114 mEq/l. Among other tests, a cranial CT scan was performed, which showed no intra- or extra-axial haemorrhagic lesions or space-occupying lesions, and a cranial MRI showed moderate cortical atrophy and supratentorial white matter lesions. Water restriction and withdrawal of citalopram were performed. He was discharged 10 days later with a Na of 125 mEq/l and a diagnosis of "Hyponatraemia due to SIADH secondary to citalopram".
Four weeks prior to the current admission, his new MAP prescribed sertraline 25 mg/day due to low mood, anxiety and apathy. The patient had remained without antidepressant treatment since the last admission. According to the family, during these weeks they noticed him to be progressively more clumsy at a motor level, bradypsychic and with psychomotor inhibition. The day before going to the emergency department, the dose was increased to 50 mg/day due to lack of improvement.
The patient was brought to the emergency department for an episode of intense somnolence lasting about ten minutes, which only responded to painful stimuli; on recovering he subsequently presented incoherent speech. On examination in the emergency department, the patient was in a basal state, without motor focality and oriented in time and space. The physical examination showed no significant findings and the neurological examination showed only motor slowness and a tendency to somnolence. Additional tests showed hyponatraemia of 116 mEq/l, increased urinary osmolarity (531 mOsm/kg) and decreased plasma osmolarity (254 mOsm/kg). Chest X-ray and ECG, with no relevant findings.
The patient was admitted to Internal Medicine with a diagnosis of severe hypotonic hyponatraemia secondary to thiazide treatment associated with SSRIs. Treatment with sertraline was suspended, water restriction with balance was indicated and isotonic saline solution was prescribed until plasma sodium levels normalised.
After several days of admission, an interconsultation report was sent to the Psychiatry Department for clinical assessment and decision regarding antidepressant drug treatment. The patient presented depressive symptoms with high levels of anxiety and intense hypochondriacal fears. Both the patient and his family demanded another antidepressant treatment, as in recent years there had been a clear clinical worsening in the periods in which he had been without treatment. It was decided to start treatment with mirtazapine 15 mg/day with an increase to 30 mg/day after the first week of treatment and to carry out weekly controls of plasma sodium levels during the first 3-4 weeks and then more frequently. At discharge, antihypertensive treatment with enalapril is also recommended, avoiding combinations with thiazide diuretics.

