Investigations
1st investigations to order
FBC
Test
Part of the routine investigation of any patient with suspected renal disease. Performed at least annually or more frequently as renal function declines.
Elliptocytosis may suggest a diagnosis of Alport syndrome with learning disability, although this is extremely rare.
Result
possible anaemia or leukocytosis; elliptocytosis if with learning disability
metabolic panel
Test
Part of the routine investigation of any patient with suspected renal disease. At least annually or more frequently as renal function declines. Serum creatinine can screen for abnormalities in GFR.
Result
may show abnormalities consistent with renal failure such as low bicarbonate, elevated potassium or serum creatinine, or low calcium; may show metabolic acidosis
fasting lipid panel
Test
Part of the routine investigation of any patient with suspected renal disease. At least annually or more frequently as renal function declines.
Result
possible dyslipidaemia
urinalysis
Test
Shows large numbers of red cells per high power field.
Morphology may suggest a glomerular origin.
Also carried out to quantify the level of proteinuria. This is an important indicator of likely progression of renal disease.
Proteinuria can also be assessed by calculating the ratio of urinary protein to serum creatinine.
May be repeated annually or more frequently if proteinuria is heavy or if nephrotic syndrome develops.
Result
haematuria and/or proteinuria
serum intact PTH
Test
With renal impairment there is loss of 1-alpha-hydroxylase in the kidney, which results in a decreased conversion of 25-hydroxyvitamin D to the active 1,25-dihydroxyvitamin D. This then causes hyperphosphataemia and hypocalcaemia with a consequent rise in PTH.
Result
may be elevated in cases of renal failure
audiometry
Test
Recommended in all cases of suspected Alport syndrome.
Result
possible high-tone sensorineural hearing loss
ophthalmoscopy
Test
Recommended in all cases of suspected Alport syndrome where additional diagnostic criteria are required.
Result
possible corneal and/or retinal abnormalities; lenticonus (bulging of the lens capsule and the underlying cortex), maculopathy and early-onset cataract
renal ultrasound
Test
Also excludes any structural abnormality of the renal tract that may suggest an alternative diagnosis.
Result
normal-sized or small smooth kidneys
renal biopsy
Test
Part of the diagnostic work-up of a patient with suspected Alport syndrome or any abnormality warranting renal biopsy (e.g., undiagnosed chronic renal insufficiency or unexplained proteinuria and haematuria).[35] Should only be offered after molecular testing.
Result
features on electron microscopy typical of Alport syndrome; immunohistochemical analysis of type IV collagen chain distribution may reveal loss of staining in males and absent or discontinuous staining in females
ECG
Test
Routine investigation for a patient with underlying renal disease and hypertension.
Result
normal or may show evidence of left ventricular hypertrophy
Investigations to consider
molecular genetic testing
Test
Can confirm diagnosis, identify mode of inheritance and predict phenotype, and help in offering prenatal and pre-implantation genetic diagnosis and living kidney donor assessment (see Aetiology).[22]
Next generation sequencing analysis of all the Alport syndrome associated genes is available and affordable in many different health care settings. Should ideally be carried out after clinical genetics review.[16]
Linkage analysis can be performed if sufficient family members of known disease status are available for study.[23][24]
Result
identification of pathogenic mutation in COL4A5 (in X-linked Alport syndrome) or COL4A3/4 (in autosomal Alport syndrome)
skin biopsy
Test
Should be considered if immuno-fluorescent staining for alpha-5(IV) is available locally as part of the diagnostic work-up for X-linked Alport syndrome (XLAS) in males and females.[34][38] In XLAS, staining for alpha-5(IV) is absent in 80% of males and absent or discontinuous in about 60% of females.
Result
abnormal discontinuous staining for alpha-5(IV) in the epidermal basement membrane
echocardiogram
Test
Routine investigation for a patient with underlying renal disease and hypertension.
Result
possible left ventricular hypertrophy and aortic abnormalities
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