Differentials
Essential hypertension
SIGNS / SYMPTOMS
No specific signs or symptoms. More frequently causes milder hypertension.
INVESTIGATIONS
Diagnosis of exclusion.
Acute kidney injury
SIGNS / SYMPTOMS
No specific signs or symptoms. Can be associated with difficult-to-control hypertension and abnormal volume status regulation.
INVESTIGATIONS
GFR is low.
Urinalysis and sediment evaluation may show proteinuria, haematuria, cells, casts, or crystals.
Renal artery dissection
SIGNS / SYMPTOMS
Difficult to differentiate clinically.
Although fibromuscular dysplasia places patients at a greater risk of renal artery dissection, spontaneous dissection of the renal artery or the aorta (involving the renal arteries) may cause severe hypertension and loss of kidney function.
INVESTIGATIONS
Ultrasound, MR angiography, CT angiography, or conventional angiography will highlight an intimal flap.
Renal artery embolism
SIGNS / SYMPTOMS
History of other vascular disease, possibly history of catheterisation, although it may occur spontaneously.
INVESTIGATIONS
GFR may be reduced.
Eosinophilia may be present.
Lactate dehydrogenase level is commonly elevated.
Urinalysis and sediment evaluation may show WBCs and eosinophils.
Chronic kidney disease
SIGNS / SYMPTOMS
Patients with chronic kidney disease typically have difficult-to-control hypertension and volume status, which may mimic RAS. Furthermore, diabetes and hypertension are both causes of chronic kidney disease as well as RAS.
INVESTIGATIONS
GFR is typically reduced.
Urinalysis and sediment evaluation often show markers of kidney damage such as proteinuria or cells, casts, or crystals.
Kidney biopsy may demonstrate glomerular, tubular, or interstitial pathology.
Coarctation of the aorta
SIGNS / SYMPTOMS
Blood pressure different in arms and/or legs.
INVESTIGATIONS
Blood pressure in arms and legs demonstrates discrepancy.
Echo, MRI, and aortography may highlight coarct.
Primary hyperaldosteronism
SIGNS / SYMPTOMS
Resistant or accelerated hypertension, adrenal adenoma.
INVESTIGATIONS
Plasma potassium may be low while urine potassium may be high.
Plasma aldosterone-to-renin ratio >20.
Adrenal CT may highlight a unilateral mass or bilateral gland enlargement.
Urine aldosterone is not suppressed after oral salt load.
Adrenal venous sampling demonstrates non-suppressible hormone levels.
Cushing's syndrome
SIGNS / SYMPTOMS
Moon face, buffalo hump, obesity, abdominal striae, possible history of corticosteroid administration.
INVESTIGATIONS
High morning plasma cortisol after 1 mg dexamethasone at bedtime.
Urinary cortisol levels are elevated.
Adrenal CT demonstrates gland enlargement.
Pituitary imaging may demonstrate adenoma.
Phaeochromocytoma
SIGNS / SYMPTOMS
Resistant or accelerated hypertension, possibly episodic hypertension.
INVESTIGATIONS
Plasma-free metanephrines, urine metanephrines and catecholamines, and plasma normetanephrine are elevated.
Adrenal CT and scintigrams may demonstrate a mass.
Vasculitis
SIGNS / SYMPTOMS
Usually with systemic symptoms (e.g., fever, weight loss), progressive kidney failure.
INVESTIGATIONS
Decreased GFR may be present.
Urinalysis and sediment may show proteinuria and haematuria.
Serological testing may be abnormal.
Use of this content is subject to our disclaimer