HIGH BLOOD PRESSURE
History
Nikita is a 12-year-old Asian girl who is referred to paediatric outpatients by her GP because she has high blood pressure and is overweight. She came to see her GP because she had an ear infection and the GP measured her BP because she is overweight. It was raised and he repeated it a week later when Nikita had recovered and the reading was the same. Nikita is otherwise well but gets headaches about once every 2 weeks. There is no nausea or vomiting. The headaches have been occurring for about 2 years. She had grommets inserted when she was 4 years old. She started her periods 1 year ago and her periods are regular. She is on no medication. Her mother has hypertension.
Examination
Her height is 167 cm (91st centile), weight 85.3 kg (99.6th centile) and body mass index (BMI) is 30.6 kg/m2. Her blood pressure is 146/82 mmHg. There are no dysmorphic features. She has no cardiovascular signs and femoral pulses are palpable. There are pink abdominal striae. There is no organomegaly or abdominal masses. There are no neurological or respiratory signs
INVESTIGATIONS (Done by the GP)
Normal
Full blood count Normal
Sodium 137 mmol/L 135–145 mmol/L
Potassium 4.1 mmol/L 3.5–5.0 mmol/L
Urea 6.2 mmol/L 1.8–6.4 mmol/L
Creatinine 67 µmol/L 44–88 µmol/L
Bone chemistry Normal
Liver function tests Normal
Thyroid function tests Normal
Urine dipstick Blood – nil
Protein – trace
Leucocytes – nil
Nitrites – nil
Questions
• What is the most likely cause of the hypertension in this child?
• What further investigations would you perform?
• What would be your management plan?
Medicine
This child is most likely to have essential (idiopathic) hypertension. This is associated with obesity. Hypertension in pubertal children is most often essential but in prepubertal children there is often a cause. However, first the diagnosis of hypertension needs to be confirmed. The blood pressure should only be measured after the child has been seated and calm for 5 min. The BP cuff should cover more than three-quarters of the upper right arm and the bladder 50 per cent of the arm circumference (too small a cuff will lead to an artificially high blood pressure). The reading should be repeated at least once. In cases of mild hypertension with no target organ damage (the majority), the blood pressure should be repeated at least three times at weekly intervals to determine if the elevation is sustained. Ideally, 24-hour ambulatory blood pressure monitoring should also be carried out to confirm the diagnosis and to rule out white-coat hypertension. There are charts available with centiles for childrens’ blood pressure which are dependent on sex, age and height centile. A systolic or diastolic blood pressure 95th centile denotes hypertension. Headaches can occur in hypertension. In Nikita’s case, the cause may be hypertension or the commoner tension type headache. Any obese child can get striae; in Cushing’s disease they tend to be purple rather than pink.
Causes of hypertension (use the mnemonic – CREED)
• Cardiological, e.g. coarctation of the aorta
• Renal, e.g. glomerulonephritis, renal artery stenosis
• Essential
• Endocrine, e.g. thyrotoxicosis, Cushing’s disease, phaeochromocytoma
• Drugs, e.g. steroids, contraceptive pill, amphetamines
To confirm the diagnosis, 24-hour ambulatory blood pressure monitoring should be performed. Renal disease is the commonest cause of hypertension and a renal ultrasound (ideally with Doppler studies of the renal vessels) should be done. Cardiac pathology is the second commonest cause. The presence of palpable femoral pulses makes a coarctation unlikely. However, an ECG should still be performed to see if the hypertension has led to left ventricular hypertrophy. To investigate the consequences of obesity, a fasting glucose (to rule out type 2 diabetes) and fasting cholesterol and triglyceride levels should be done. Further investigations will depend on confirmation of the hypertension by the ambulatory monitoring and clinical symptomatology. The management plan should include lifestyle changes. A referral to a dietician should be done and advice given about a low-salt and a low-fat diet. A total of 1 hour of exercise every day should be recommended. If the raised blood pressure is confirmed, a betablocker or calcium channel blocker could be used.
KEY POINTS
• The blood pressure should be measured with the child calm, with the right size of cuff, and be repeated.
• Published centile charts should be consulted.
• Hypertension in pubertal children is most often essential but in prepubertal children there is usually a cause (most commonly renal).
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