RENAL HYPERTENSIONالدكتور خلدون ذنون- كلية طب نينوى- المرحلة الرابعة
ObjectivesThe student should pay attention to the following pillars:
1. Many kidney diseases are responsible for secondary hypertension.
2. Suspect secondary hypertension in younger age group and resistant to
3. Special investigations are needed to diagnose renal hypertension.
4. Polycystic kidney disease is an important hereditary cause of renal
5. Types, clinical presentation, and management of renal artery stenosis.
6. Severe hypertension and renal failure is an important cause of
morbidity and mortality in scleroderma.
DefinitionHypertension due to renal diseases(secondary HTN).It causes <5% of all cases of HTN. It is one of the causes of refractory HTN.
CausesRenal vascular diseases e.g renal artery stenosis , vasculitis , eclampsia , pre-eclampsia , scleroderma .
Parenchymal renal diseases e.g GN , interstitial nephritis , chronic pyelonephritis.
Polycystic renal diseases.
Others : HUS , TTP, juxtaglomerular cell tumor , nephroblastoma .
Mechanism of renal HTN ( Activation of the renin-angiotensin-aldosterone system . ( Na & fluid retention.
POLYCYSTIC KIDNEY DISEASES
Infantile : autosomal recessive , rare , associated with hepatic fibrosis , fatal .
Adult polycystic kidney disease (APKD): autosomal dominant , more common .
Small cysts lined by proximal tubular epithelium , present in infancy & enlarge at variable rate during growth .
Clinical featuresSymptoms appear later in life .
After 20y insidious onset of HTN .
Loin discomfort .
Acute loin pain or renal colic due to haemorrhage in to a cyst .
Urinary tract infection .
Renal failure .
Palpable kidneys .
30% hepatic cysts .
Berry aneurysms of cerebral vessels .10% develop subarachnoid haemorrhage .
Associated with mitral & aortic regurgitation , colonic diverticulae , abdominal wall hernias.
At about 50y age 50% require dialysis.
InvestigationsUltrasound: detect multiple cysts on both sides.
MR-angiography of brain for aneurysms.
Specific genetic diagnosis .
( Control of BP.
( Treatment of UTI .
( Salt losers should be given NaCL or Na bicarbonate .
( Treat CRF. Dialysis and transplantation.
RENAL ARTERY STENOSIS( RAS)Pathology
1. Atheromatous RAS : most common cause , >50y age .
2. Fibromuscular dysplasia : <50y age , congenital band of fibrous tissue around the artery . presents as HTN 15-30Y.
Both types cause poststenotic dilatation .
Stenosis : ostial , proximal , distal .
Stenosis < 50% is not haemodynamically significant .
Unilateral disease : unaffected kidney show hypertensive nephrosclerosis , while renal parenchyma on the stenosed side may be protected but with (GFR.
Clinical presentationHypertension: seen in young age group is severe , of recent onset or difficult to control or in atheromatous type with past history of hypertension or ischemic heart disease develops recent hypertension difficult to control.
Recurrent pulmonary edema.
Renal function has deteriorated on ACEI.
Acute renal infarction: loin pain and hematuria.
If bilateral or single kidney may lead to renal failure.
Evidence of vascular disease elsewhere especially lower limbs , > 50y age .
InvestigationsRenal arteriograpyh gives the definitive diagnosis .
U/S : decreased kidney size on the affected side . Doppler U/S assess blood flow through the stenosis.
Renal isotope scanning: delayed uptake of isotope & ( excretion of the isotope in the affected kidney.
CT and MR angio largely replaced Doppler u/s and isotope study.
Renal function tests and electrolytes.
Antihypertensives: avoid B-blockers , ACEI used with care in renal impairment as it may precipitate renal failure , ACEI are c/i in bilateral RAS .
Low dose aspirin , lipid lowering drugs .
Angioplasty- balloon dilatation with or without stenting .
Surgical resection of the stenosed segment & reanastomosis.
Conservative medical management if there is widespread atheromatous disease of the aorta .
problems with atherosclerosis : contrast nephropathy , renal artery occlusion and renal infarction , atheroemboli .
if untreated atheromatous RAS will progress to complete occlusion &
loss of kidney function in 15% of cases , in fibromuscular dysplasia
complete occlusion of the renal artery usually does not occur.
SYSTEMIC SCLEROSIS (SCLERODERMA)Connective tissue disease , intimal cell proliferation & narrowing of the intra-renal arteries.
Usually present as (scleroderma renal crisis) : severe HTN , microangiopathy , oliguric renal failure & marked ( in plasm renin.
ACE inhibitors are the drugs of choice for control of HTN .
50% require renal replacement therapy.