Middle East Journal of Family Medicine

Coauthor: Professor Dr Muhammad Zarif
Professor of Medicine, Khyber Medical College
Peshawar, Pakistan.

Correspondence to:
Dr Hamzullah Khan MBBS
Khyber Medical College
Peshawar, Pakistan
Phone number: 0092-345-9283415
Email: hamzakmc@gmail.com,
Alternative email: hamza_kmc@yahoo.com

ABSTRACT

Objectives: To determine the frequency of causes peculiar to secondary hypertension in a tertiary care hospital of Peshawar.

Design: Prospective observational study.

Sampling: A total of seventy patients with confirmed diagnosis of secondary hypertension were randomly included.

Setting: Department of Medicine Khyber teaching hospital Peshawar.

Duration: From January 2006 to August 2007.

Methods: Relevant information was recorded from patients and a treatment chart of the patients, on a questionnaire designed in accordance with the objectives of the study.

Results: A total of 70 patients with confirmed diagnosis of secondary hypertension were randomly included. Of the total, 62.29% were males and 37.71% females. The age range of the patients was from 14-78 years with a mean age of 47.5 years. The causes of secondary hypertension were: thyrotoxicosis (34.28%), pregnancy induced hypertension and pre-eclampsia (27.14%), Cushing syndrome (17.14%), glomerulonephritis (7.14%), acromegaly and corticosteroids intake ocer a long period of time especially in rheumatoid patients (2.85%), history of oral contraceptives, NSAIDS intake over a longe period of time especially in rheumatoid patients, hypercalcemia, phaeochromocytoma, polycystic kidney and renal artery stenosis each recorded in 1.42% of cases.

Conclusion: Thyrotoxicosis, pregnancy induced hypertension and pre-eclampsia, Cushing syndrome and glomerulonephritis, in their descending order are major contributors to the development of secondary hypertension in our patients.

Key words: Secondary hypertension causes peculiar to secondary hypertension, Peshawar.

While most forms of hypertension have no known underlying cause (and are thus known as "essential hypertension" or "primary hypertension"), in about 10% of the cases, there is a known cause, and thus the hypertension is secondary hypertension (or, less commonly, inessential hypertension)¹. Isolated systolic hypertension is the most common form of hypertension, especially among patients 50 years or older. Worldwide 5% of hypertensive patients have secondary hypertension. Hyperthyroidism increases systolic blood pressure by decreasing systemic vascular resistance, increasing heart rate, and raising cardiac output. Potential cardiovascular consequences of hyperthyroidism include atrial arrhythmias (especially atrial fibrillation), pulmonary hypertension, left ventricular hypertrophy, and heart failure. The prevalence of hypertension is greater among hyperthyroid patients than euthyroid patients². Pregnancy-induced hypertension (PIH) is a form of high blood pressure in pregnancy. It occurs in about 5 percent to 8 percent of all pregnancies.

Pregnancy-induced hypertension is also called toxemia or pre-eclampsia. It occurs most often in young women with a first pregnancy. It is more common in twin pregnancies, in women with chronic hypertension, pre-existing diabetes, and in women who had PIH in a previous pregnancy³.

Cardiovascular disease is the major cause of morbidity and mortality in Cushing's syndrome and excess risk remains even in effectively treated patients. The cardiovascular consequences of cortisol excess are protean and include, inter alia, elevation of blood pressure, truncal obesity, hyperinsulinemia, hyperglycemia, insulin resistance, and dyslipidemia⁴. Renovascular hypertension (RVHT) denotes non-essential hypertension in which a causal relationship exists between anatomically evident arterial occlusive disease and elevated blood pressure. RVHT is the clinical consequence of renin-angiotensin-aldosterone activation as a result of renal ischemia. Renal artery stenosis (RAS) is a major cause of RVHT and accounts for 1-10% of the 50 million cases of hypertension in the United States⁵. The present study was designed as to determine the frequency of causes peculiar to secondary hypertension in a tertiary care hospital of Peshawar.

This prospective observational study was conducted in Department of Medicine Khyber teaching hospital Peshawar, from January 2006 to August 2007. A total of seventy patients with confirmed diagnosis of secondary hypertension were randomly included. Of total 62.29% were males and 37.71% females.

Relevant information was recorded from patients and treatment chart of the patients, on a questionnaire designed in accordance with the objectives of the study. Inclusion criteria were all patients who had established diagnosis of cirrhosis, irrespective of age and sex, admitted to the Medical department of Khyber Teaching Hospital (KTH). Exclusion criteria were all patients with essential or primary hypertension. Similarly patients with thyroid diseases or any other renal pathology that had not yet developed hypertension were also excluded. Only patients diagnosed by the consultants as patients suffering from secondary hypertension in our medical ward were included.

A detailed history of patients was taken with the help of a pre-designed questionnaire, prepared in accordance with the objectives of this study. Family history of hypertension was also recorded. The questionnaire contained preliminary information regarding age, sex, address and education of patients. It also contained information about causes of secondary hypertension. Blood pressure of each patient was recorded and hypertension was defined as systolic blood pressure more than 140 mm Hg and diastolic blood pressure more than 95mm Hg on more than one occasion⁶. Investigation reports of thyroid function tests, serum cortisole, renal function tests, radiographs and magnetic resonance angiography (MRA) for RVT, urine routine examinations and proteinuria for PIH etc were also recorded from the ward record of the patients if there were any. Finally statistical analysis of the data was performed and association of risk factors with cirrhosis was studied.

Sampling: A total of 70 patients with confirmed diagnosis of secondary hypertension were randomly included. Of the total 62.29% were males and 37.71% females (Table 1).

Age range of patients: The age range of the patients was from 14-78 years with a mean age of 47.5 years. The MODE value of age in our patients was 45 years age (Table 2).

Causes of secondary hypertension: The causes of secondary hypertension were: thyrotoxicosis (34.28%), pregnancy induced hypertension and pre-eclampsia (27.14%), Cushing syndrome (17.14%), glomerulonephritis (7.14%), acromegaly and corticosteroid intake for a long period of time especially in rheumatoid patients at(2.85%), history of oral contraceptives, NSAID intake for a long period of time, especially in rheumatoid patients, hypercalcemia, phaeochromocytoma and Polycystic kidney and renal artery stenosis each recorded in 1.42% cases (Table 3).

Hypertension is one of the most common worldwide diseases afflicting humans. Because of the associated morbidity and mortality and the cost to society, hypertension is an important public health challenge. Hypertension is the most important modifiable risk factor for coronary heart disease (the leading cause of death in North America), stroke (the third leading cause), congestive heart failure, end-stage renal disease, and peripheral vascular disease⁷.

The average systolic blood pressure (SBP) of people aged 30 years or above estimated in 2005 (date from urban population only) reveals as 130-139 mm Hg for Pakistani adults, 120-129 mm Hg for Indians, 140 mm Hg or above for Senegal and below 120 mm Hg for adults in Thailand⁸. Based on recommendations of the Seventh Report of the Joint National Committee of Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC VII), the classification of blood pressure (expressed in mm Hg) for adults aged 18 years or older is as follows:

Normal - Systolic lower than 120, diastolic lower than 80
Pre-hypertension - Systolic 120-139, diastolic 80-99

Stage 2 - Systolic equal to or more than 160, diastolic equal to or more than 100⁹.

Five percent of adults with hypertension have the secondary form of hypertension, the cause and pathophysiologic processes of which are known. Characteristics that may suggest secondary hypertension such as abdominal diastolic bruits (renovascular hypertension), decreased femoral pulses (coarctation of the aorta), or bitemporal hemianopias (Cushing's disease).

A combination of a good history and physical examination, astute observation, and accurate interpretation of available data usually are helpful in the diagnosis of a specific causation¹⁰. In the present study 34.28% of cases of secondary hypertension were attributed to hyperthyroidism. Similar findings are reported from various studies^11-12. The second most important cause of secondary hypertension is pregnancy induced hypertension and pre-eclampsia (27.14%). It has been reported from our country research study that eclampsia is the second major cause of maternal mortality in Pakistan and its incidence is 2.31% in our country ¹³. Cushing syndrome was encountered in 17.14% cases of the secondary hypertension.

Hypertension is one of the most distinguishing features of endogenous Cushing's syndrome, as it is present in about 80% of adult patients and in almost half of children and adolescent patients. Hypertension results from the interplay of several pathophysiological mechanisms regulating plasma volume, peripheral vascular resistance and cardiac output, all of which may be increased.

The therapeutic goal is to find and remove the cause of excess glucocorticoids, which, in most cases of endogenous Cushing's syndrome, is achieved surgically¹⁴. Five cases (7.14%) of the secondary hypertension attributed to glomerulonephritis. Our findings correlated with the findings of Arnaud L, et al¹⁵. Acromegaly and corticosteroid intake for a long period of time, especially in rheumatoid patients, was recorded in 2.85% patients. Patients with acromegaly have a significant morbidity and mortality, associated with cardiovascular disease.

Acromegaly is often complicated by other diseases such as diabetes mellitus, hypertension, and coronary artery disease, so the existence of acromegalic cardiomyopathy remains uncertain¹⁶.

From this study we concluded that thyrotoxicosis, pregnancy induced hypertension and pre-eclampsia, Cushing syndrome and glomerulonephritis, in their descending order are major contributors to the development of secondary hypertension in our patients. Acromegaly and corticosteroid intake for a long period of time, especially in rheumatoid patients, are moderate risk factors, while history of oral contraceptives, NSAID intake for a long period of time, especially in rheumatoid patients, hypercalcemia, phaeochromocytoma, polycystic kidney and renal artery stenosis are minor contributors to the development of secondary hypertension.