BLOOD SCIENCES Plasma cell
Hyperviscosity complications Hyperviscosity syndrome is a serious condition. Without treatment, it can lead to artery blockages and reduced blood flow.4
This diminished flow may lead to Red marrow
Normal antibodies
severe repercussions throughout the body, such as hypertension, irregular bleeding, sepsis, deficits in vision and hearing, as well as organ failure resulting from hypoperfusion and cell aggregation. In children, reduced blood flow can affect growth and development.
Yellow marrow
Diagnosis and tests Healthcare professionals generally identify hyperviscosity syndrome through blood investigations. They might utilise:5 n Plasma viscosity (PV), serum viscosity or whole blood viscosity tests to evaluate blood thickness.
n Arterial blood gas test to measure oxygen and carbon dioxide.
Abnormal plasma cells
n Full blood count (FBC). n Bilirubin level. n Creatinine test to evaluate kidney function.
n Liver function test. n Protein tests. n Blood glucose.
Clinical conditions associated with hyperviscosity
Abnormal antibodies
Multiple myeloma.
Hyperviscosity in adults is commonly associated with various clinical conditions, as shown in Table 1. In neonates (newborn) it can also be a complication in twin pregnancy where one twin preferentially receives more of the maternal circulation than the other. A common cause of HVS is an increase in the viscosity of plasma due to increased circulating monoclonal (paraproteinaemic) and polyclonal immunoglobulins. The excessive intravascular paraproteins result in a rheologically impaired microcirculation and possible hypervolaemia.1 Increases in fibrinogen, α2
macroglobulin and immunoglobulins increase both plasma viscosity and red cell aggregation which correlate well with measurements made by plasma viscosity and sometimes ESR methods. However, in extreme cases of plasma hyperviscosity, the suspending plasma may be so viscous that it decreases cell aggregation, causing the erythrocyte sedimentation rate (ESR) to fall to
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low or zero levels in addition to the increased plasma density decreasing the sedimentation of aggregates. Hence this leads to a misleading false-negative result in the ESR.
Symptoms of hyperviscosity HVS is characterised by a significant increase in plasma protein concentration or cellular component changes causing impairment of blood flow. Patients with this condition frequently present with following symptoms:2,3 n Plethora. n Cyanosis. n Neurological symptoms (headache, dizziness, vertigo, confusion, coma).
n Visual problems (blurred vision, double vision, vision loss).
n Spontaneous bleeding (epistaxis, menorrhagia, melaena and severe itching).
n Cardiopulmonary symptoms (shortness of breath, hypoxaemia, hypotension).
n Fatigue and weakness. n Hearing changes (tinnitus and hearing loss).
n Multiple myeloma Multiple myeloma (MM) is an immunoproliferative disorder associated with increased numbers of abnormal plasma cells in the bone marrow.6
When
plasma cells are healthy, they produce antibodies (immunoglobulins). MM is characterised by an excess production of a single paraprotein, commonly IgG, but may also be IgM, IgA, IgD, or IgE. This can cause complications such as bone thinning, spontaneous and pathological fractures, and recurrent infections in the bone.
The association of MM and raised PV is well established, with the UK’s National Institute for Health and Care Excellence recommending that a PV test should be conducted for individuals suspected of having MM.7
The association is most emphasised in IgM because ‘the large star-shaped IgM pentamers are highly viscous’,8
and less
so in IgG and IgA, though an association is still apparent. For example, according to Rogers and Estes: “About 25% of hyperviscosity syndrome (HVS) cases secondary to myelomas are caused by IgA, followed by IgG myelomas.” Multiple myeloma and plasma viscosity
were discussed in a 1981 report by Harkness, who stated that HVS, which arises “from the marked increase in the viscosity of the plasma”, occurs in
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