Secondary hypertension Hypertension secondary to an identifiable cause , seen in about 5 % to 10 % cases
When to suspect -severe or resistant hypertension onset at a young age ie < 30 yrs with ○ no risk factors as family history or obesity ○ ↑ common in younger people- close to 30 % in those 18-40 yrs malignant or accelerated hypertension acute rise in BP in a patient with previous normal readings absence of family h/o hypertension presence of target organ damage hypertension associated with electrolyte disorders onset of diastolic hypertension in patient older than 65 non dipping or reverse dipping during 24 hr ambulatory monitoring ( ie night time BP does not dip ( normal 10 % ) relative to day time BP.
more than expected drop in potassium with a small dose of diuretic more than expected decrease in GFR with a small dose of an ACE inhibitor ( ? renal artery stenosis ) BP drops with treatment but remains quite labile.
A wide variety of condition may cause 2ary hypertension – the following clues may help in narrowing down the possibilities /approach to further management.
Agewise –Children < 12 -renal parenchymal disease and coarctation of aorta
Adolescents 12-18 -renal parenchymal disease and coarctation of aorta
Young adults ( 19-39 yrs ) fibromuscular dysplasia , renal parenchymal disease
Middle age adults 40-65 yrs – primary aldosteronism , obstructive sleep apnoea , Cushing’s syndrome , pheochromocytoma.
Older adults -atherosclerotic renovascular disease , renal failure , hypothyroidism
NSAIDs Oestrogen , androgens Steroids Illicit drug use – amphetamines , cocaine , MDMA Certain psychiatric drugs as buspirone , carbamazepine , clozapine , fluoxetine , lithium , tricyclic antidepressants Decongestants Use of herbal medications as ephedra , ginseng , ma huang , yohimbine
Renal parenchymal diseases – for e,g chronic kidney disease , polycystic kidney disease , glomerulonephritis , ischaemic nephropathy Renal parencyhmal diseases are the 2nd most common cause of 2ary HT in adults Renal vascular diseases for e,g renal artery stenosis and fibromuscular dysplasia.
Primary aldosteronism Cushing’s syndrome , disease Pheochromocytoma Thyroid and parathyroid disorders Acromegaly Congenital adrenal hyperplasia.
Vascular – coarctation of aorta Obstructive sleep apnoea Pregnancy induced hypertension.
Investigation and work up is expensive Data has shown that the common causes of 2ary hypertension include ○ obstructive sleep apnoea ○ renal parenchymal disease ○ renal artery stenosis ○ primary aldosteronism ○ drugs History taking should be tailored to screening for the most common causes
FBC ( polycythemia in OSA ) Thyroid fucntion tests Hyperparathyroidism – calcium and PTH level Urinalysis – proteinuria in renal parenchymal disease & serum creatinine Renal parenchymal disease- consider renal US if creatinine conc and / or urinalysis are abnormal / MRA renal arteries CXR – coarctation of aorta 24 hr BP monitor- can be very helpful as it allows to exclude white coat hypertension , assess treatment adherence , confirm the presence of resistant hypertension and assess the dipping status Primary aldosteronism or Conn’s syndrome will be with arterial hypertension , suppressed plasma renin activity and ↑↑ aldosterone secretion ○ hypokalaemia may be accompanied by metabolic alkalosis ○ positive aldosterone-to-renin ration with elevated Urinary catecholamine metabolites ( vanillylmandelic acid , metanephrines , normetanephrines ) would be ↑↑ in phechromocytoma Acromegaly ↑↑ growth hormone levels.
- Hegde S, Aeddula NR. Secondary Hypertension. [Updated 2021 Jun 25]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK544305/
- Puar, Troy Hai Kiat et al. “Secondary hypertension in adults.” Singapore medical journal vol. 57,5 (2016): 228-32. doi:10.11622/smedj.2016087
- Charles L, Triscott J, Dobbs B. Secondary Hypertension: Discovering the Underlying Cause. Am Fam Physician. 2017 Oct 1;96(7):453-461. PMID: 29094913.
- Secondary causes of hypertension https://oxfordmedicine.com/view/10.1093/med/9780198784906.001.0001/med-9780198784906-chapter-566
- Chapter 13. Secondary hypertension. Hypertens Res 37, 349–361 (2014). https://doi.org/10.1038/hr.2014.16
- Stefano F. Rimoldi, Urs Scherrer, Franz H. Messerli, Secondary arterial hypertension: when, who, and how to screen?, European Heart Journal, Volume 35, Issue 19, 14 May 2014, Pages 1245–1254, https://doi.org/10.1093/eurheartj/eht534