Acute kidney injury is a common complication of COVID-19, especially in diabetic patients.

Hepatic function Patients with abnormal liver function tests are at a significantly higher risk of developing severe disease and complications such as pneumonia.11 Significantly elevated bilirubin levels, three times the upper limit, have been observed in COVID-19 patients.11,12

The diazo method is commonly utilised in bilirubin testing; however, superior methods exist. The vanadate oxidation (VO) method has many advantages particularly in haemolytic and lipaemic samples. These advantages are particularly evident in neonatal and infant populations where haemolysis is extremely common. Moreover, the VO method offers a wider analytical measurement range.13 Other liver function markers are known to be elevated in COVID-19 patients, including both aspartate aminotransferase (AST) and alanine aminotransferase (ALT), with markers such as albumin decreased.

Importance of Lp(a) testing Lipoprotein(a) (Lp[a]) is a strong independent marker of coronary heart disease risk in patients with heterozygous familial hypercholesterolemia (HeFH) and has recently been identified as a key risk marker of cardiovascular complications in COVID-19 patients. Those with either baseline elevated Lp(a) or those whose Lp(a) levels increased following SARS- CoV-2 infection, or both, may be at a significantly increased risk of developing thromboses. Consideration should be given to measurement of Lp(a) and the prophylactic anticoagulation of infected patients to reduce the risk. Elevated Lp(a) levels may also cause acute destabilisation of pre-existing but quiescent atherosclerotic plaques, which could induce an acute myocardial infarction or stroke.14

Significantly elevated bilirubin levels, three times the upper limit, have been observed in COVID-19 patients.

The biggest challenge with Lp(a)

measurement is the size heterogeneity of the apo(a) isoforms, resulting in the underestimation or overestimation of Lp(a) concentrations. In immunoassays, the variable numbers of repeated KIV-2 units in Lp(a) act as multiple epitopes. This is where standardisation across calibrators is vital. Unless the calibrants have the same range of isoforms as test samples, those with higher numbers of the KIV-2 repeat will represent with an overestimation in Lp(a) concentrations, and those with smaller numbers of the KIV-2 repeat will represent with an underestimation. The smaller isoforms are strongly associated with higher Lp(a) concentrations.15 The gold-standard Lp(a) method is the Northwest Lipid Metabolism and Diabetes Research Laboratory (NLMDRKL) method, which employs an isoform- insensitive antibody and is meticulously calibrated with well-characterised material; however, this test is not commercially available.15

Lp(a) assays that are standardised to

the World Health Organization/ International Federation of Clinical Chemistry (WHO/IFCC) reference material, transferring values from mg/dL to nmol/L, are more uniform. The assay considered the most reliable commercially available Lp(a) assay is so because:15 n isoform size variations are reduced as a range of calibrators from separate pools of serum are used, covering a range of Lp(a) concentrations

n isoform size and concentrations are inversely correlated – better matching calibrants with test samples

n methods are calibrated in nmol/L and traceable to WHO/IFCC reference material and give acceptable bias compared with the NLMDRL gold- standard method.


Importance of internal quality control

Up to 70% of medical decisions are based on laboratory data. Consequently, it is imperative that the information generated by the laboratory is accurate, timely and readily understandable by the end user. Quality control (QC) is run alongside the patient sample to determine the validity of the assay in accordance with the specifications.16

Consequently, QC

ensures the accuracy of patient sample results. Quality control samples should be commutable, meaning the controls react to the test system in the same manner as the patient sample, thus helping laboratories to meet the ISO 15189:2012 requirement and ultimately ensuring accurate and reliable instrument performance.17

ISO 15189:2012 states: “The laboratory should choose concentrations of control materials, wherever possible especially at or near clinical decision values, which ensure the validity of decisions made.” Furthermore, ISO 15189:2012 also states: “Use of independent third-party control materials should be considered, either instead of, or in addition to, any control materials supplied by the reagent or instrument manufacturer.” These requirements highlight the fact that third-party controls should be employed to challenge laboratory instruments throughout the patient reportable range. The presence of analytes at clinically relevant decision levels not only aid in ensuring accurate instrument performance but also maximise laboratory efficiency through the elimination of additional low/high concentration controls, which is an unnecessary additional expense.18 During the SARS-CoV-2 pandemic,


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