Prognosis
Insight into expectations
Laboratory tests in combination with scientific knowledge about (the development of) diseases provides insight into the probable course and outcome of the disease. The expectation pattern is based on the observed course of the disease in the largest possible group of patients with the same disease at the same stage.
Below are examples of the added value of laboratory testing for prognosis:
Cardiovascular
-
Heart failure
BNP and NT-proBNP
When the heart muscle experiences increased stress, BNP (Brain-type Natriuretic Peptide) is released from heart muscle cells. BNP causes blood vessels to dilate, reducing the heart strain. Along with BNP, the physiologically inactive byproduct NT-proBNP is also released. Blood levels of both compounds provide insight into heart failure (severity). Because multiple causes can lead to elevated BNP and NT-proBNP, this test's strength lies primarily in ruling out heart failure when there is strong clinical suspicion of the condition. The test is also suitable for following up medication effects (monitoring) and estimating heart failure risk (prognosis).
Cancer
-
Prostate cancer
Prostate Health Index (PHI)
PSA exists in blood in both free and bound forms, along with various PSA precursors. The prostate health index (PHI test) combines test results of three different isoforms: total PSA, free PSA, and [-2]proPSA. The quotient of [-2]proPSA and free PSA multiplied by the square root of total PSA yields the PHI index. This combination test is three times more sensitive than a PSA test alone and is thus a more reliable predictor of prostate cancer.
-
Lung cancer
ALK mutation test
In only three to five percent of all lung cancer cases is there an ALK gene mutation. For treating this small subgroup, a targeted and effective medication has been developed: crizotinib, an ALK receptor tyrosine kinase inhibitor. Using the ALK mutation test, patients who would benefit from this expensive treatment can be selected.
The ALK mutation test detects rearrangements in the ALK gene based on fluorescence in-situ hybridization (FISH). The test is performed on prepared tumor tissue. The ALK mutation test is a so-called companion diagnostic, a combination of predictive test and medication.
EGFR mutation test
For patients with confirmed EGFR mutations, specific treatments are possible with tyrosine kinase inhibitors (TKIs), such as erlotinib, gefitinib, and afatinib. The EGFR mutation test can select patients who would benefit from this expensive treatment. The mutation can be demonstrated through DNA analysis of blood plasma using PCR. The EGFR mutation test is a ‘companion diagnostic’, combining predictive testing and medication.
-
Melanoma
BRAF mutation test
The BRAF mutation test detects V600E, V600K, and V600D mutations. The molecular test is based on DNA analysis using PCR technology and is performed on prepared tumor tissue. The test is a so-called companion diagnostic, combining predictive testing and medication. Patient selection for treatment with BRAF inhibitors is based on BRAF mutation tests.
Renal
-
Renal function
Creatinine blood test
This test measures blood creatinine levels. Creatinine production depends on body height and muscle mass, resulting in typically higher values for men compared to women and children.
Creatinine urine test
Creatinine clearance indicates the kidneys' ability to filter blood and excrete waste products through urine. A 24-hour urine creatinine measurement provides comprehensive information about kidney function.
Combined creatinine and cystatin C testing
Elderly typically have lower blood creatinine levels due to reduced muscle mass. Including cystatin C measurement alongside creatinine provides more reliable kidney function assessment, particularly in elderly patients.
Rheumatic Disorders
-
Rheumatoid Arthritis
Anti-CCP test
In rheumatoid arthritis (RA), the autoimmune response involves developing specific antibodies against citrullinated proteins. These are proteins where the amino acid arginine has been converted to citrulline. The immune system recognizes citrullinated proteins as foreign, resulting in antibody production - known as anti-citrullinated protein antibodies (ACPAs). These antibodies, highly specific for RA, are detectable in blood. They often appear very early in disease progression, sometimes long before symptoms develop, making them excellent biomarkers for early RA detection. The widely used anti-CCP test (anti-cyclic citrullinated peptide) is based on these ACPAs. Anti-CCP is measured in serum using ELISA. Combined with clinical presentation and RF testing, this anti-CCP test aids in RA diagnosis.
Anti-MCV test
Another biomarker in the ACPA family is anti-mutated citrullinated vimentin (anti-MCV). This diagnostic marker is measured in serum using ELISA. While the anti-CCP test uses synthetic antigens (2-3 epitopes), the anti-MCV test employs natural human antigens (40 epitopes). This makes the anti-MCV ELISA highly sensitive and specific for early-stage RA detection. The sensitivity for early RA detection appears to increase further when both anti-CCP and anti-MCV are measured. The anti-MCV test is also valuable for disease severity prognosis and therapy monitoring.
