Secondary hypertension


The two major types are:

  • Primary or essential hypertension, that has no known cause, is diagnosed in the majority of people.
  • Secondary hypertension is often caused by reversible factors, and sometimes curable.

Secondary hypertension

About 5% of hypertension cases have an underlying disorder of an organ in the body, and are called secondary. Certain medication or recreational drugs can also cause secondary hypertension.

Depending on the cause, this type of hypertension can often be cured or at least greatly improved.

Findings suggestive of secondary hypertension:

  • Sudden onset.
  • Young age, like children or young adults.
  • Onset after the age of 50 with no previous raised BP.
  • Very severe hypertension and unusual symptoms.
  • Resistance to treatment with medication.
  • No family history of primary/essential hypertension.
  • Certain abnormal findings on examination.
  • History of blood vessel disease.
  • Raised blood pressure in a previously well-controlled hypertensive patient, that has not stopped or changed medication.

Secondary Hypertension may be caused by:

  • Kidney damage or impaired function
    This accounts for most secondary forms of hypertension.  The kidneys play a major role in the control of fluid-balance and blood pressure in the body.  Examples are inflammatory kidney diseases, as well as damage due to drugs or diabetes. Narrowing of the artery supplying the kidney, is called renal stenosis, and is often curable with surgery.
  • Tumours or overactivity of the adrenal gland
    Tumors or overactivity in the different sections of the adrenal gland lead to the oversecretion of certain hormones. The end result of this is a raise in blood pressure.  One type of tumour, pheochromocytoma, is often curable. 
  • Thyroid dysfunction
    Both an overactive and an underactive thyroid can lead to hypertension. Thyroid function can easily be determined with a blood test and is usually well-controlled with treatment.
  • Coarctation of the aorta.
    An inborn, abnormal narrowing of the aorta. This is the blood vessel that carries blood from the heart to the rest of the body. This usually occurs in the chest, just beyond the blood vessels carrying blood to the arms.
  • Pregnancy related conditions
    Preeclampsia and eclampsia are serious conditions that can occur in pregnancy. These conditions can be cured by terminating the pregnancy, like early delivery by caesarean section. Hypertension in pregnancy can be controlled with medication.

    Having uncomplicated hypertension need not prevent a woman from becoming pregnant. However, it should be discussed with an experienced doctor, preferably before the pregnancy.

  • Sleep Apnea Syndrome
    This is an underdiagnosed condition, that decreases the quality of life of those suffering from it. Sleep apnea raises blood pressure. It is a stroke and cardiac risk factor. This condition, also called Obstructive Sleep Apnea needs to be treated by a multidisciplinary team, that specialises in sleep disorders.
  • Medication, recreational drugs, drinks and food
    Hypertension caused by the above is usually curable, when a person stops taking the offending substance. Many over-the-counter drugs are included in this group, as are illicit drugs like Ecstasy, amphetamines and cocaine. Excessive consumption of caffeine, nicotine and alcohol may also raise the blood pressure.

    It is imperative to be absolutely honest with your health professional concerning your habits and self-medication. Birth control pills can also contribute to an increase in blood pressure in some women, especially if they also smoke and are older than 35.

(Dr Kathleen Coetzee, MBChB )

Read more:
Incidence and risk factors of CRF
Am I at risk for hypertension?

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