Investigations
1st investigations to order
FBC
Test
Neutropenia is the hallmark of the condition. It should be persistent (>6 months) so the test may need to be repeated several times.
Neutrophil count <1 x 10⁹/L (<1000/microlitre) is classed as severe and is a risk factor for infection.[13]
Patients with concurrent infections may have a normal or slightly elevated neutrophil count that resolves once infection is treated.
Anaemia may be due to chronic disease or hypersplenism. Thrombocytopenia may be present because of hypersplenism.
Anaemia and thrombocytopenia are not required for diagnosis of FS.
Result
neutrophil count <2 x 10⁹/L (<2000/microlitre); anaemia; thrombocytopenia
peripheral blood smear
Test
Ordered if neutropenia is present, and helps rule out other haematological causes of neutropenia, including large granular lymphocyte syndrome.
Result
neutropenia and absence of other pathological cell types
serum erythrocyte sedimentation rate
Test
Non-specific elevation is typical in FS.
Sensitivity and specificity of this test are low.
Result
elevated
serum CRP
Test
May be elevated in FS, particularly if there is concurrent infection.[2]
Sensitivity and specificity of this test are low.
Result
elevated
LFTs
Test
Alkaline phosphatase and aminotransaminase levels may be mildly elevated in about 25% of patients.
Result
elevated alkaline phosphatase; elevated transaminases
Investigations to consider
serum antinuclear antibodies
Test
Found in 47% to 100% of patients with FS.[7]
Test can also be requested if systemic lupus erythematosus (SLE) or anti-TNF-induced lupus (ATIL) is suspected as a cause of neutropenia. Double-stranded DNA antibodies are more likely to be positive in high titre in SLE or ATIL.
Result
positive
serum anti-cyclic citrullinated peptide (anti-CCP) antibodies
Test
Typically positive. Titres higher than in rheumatoid arthritis patients without extra-articular manifestations.[15]
Result
elevated
ultrasound of abdomen
Test
Splenomegaly is common (>90% patients) but is not a requirement for diagnosis.
Mild hepatomegaly can also occur.
Result
splenomegaly and/or hepatomegaly
CT scan of abdomen
Test
Can be performed if ultrasound is inconclusive.
Splenomegaly is common (>90% patients) but is not a requirement for diagnosis.
Mild hepatomegaly can also occur.
CT may also show presence of lymphadenopathy, which may occur in certain haematological malignancies.
Result
splenomegaly and/or hepatomegaly
chest x-ray
Test
May be requested to investigate signs of chest infection, if suspected after clinical examination.
Result
consolidation suggesting infection
bone marrow biopsy
Test
Typically may show myeloid hyperplasia and maturation arrest, although hypocellularity and mitotic pools have also been reported.
Performed to exclude other haematological causes of neutropenia, such as myeloproliferative or lymphoproliferative disorders.[3]
Result
variable appearances
virological tests
Test
Not routine but may be considered to exclude other causes of neutropenia, especially if risk factors present for immunodeficiency or susceptibility to opportunistic viral infections.
Result
HIV-negative, cytomegalovirus-negative
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