Clinical Chem Case Study Flashcards
Red color urine
High UTP but normal UMA, with dipstick protein-.
What would you consider? (1)
Red urine: beetroot , Phenazopyridine, hematuria, menstrual bleeding, hereditary porphyria
High UTP but normal UMA: Alkaptonuria, homogentisic acid accumuation affecting benzethonium chloride method but not tetrabromophenol blue method
Typically, Alkaptonuria causes black urine
Patient has persistent low ALP, what would you suspect? (1)
Why Asfotase alfa causes low ALP value? (1)
Hypophosphatasia. confirm by high PLP (B6)
This genetic disease causes low ALP level, accumuation of substrate PPi, and therefore impeding bone mineralization.
Failure of PLP dephosphorylation leads to seizure.
Asfotase alfa is a mimic of ALP with higher enzyme activity. It causes extreme high ALP value, which in some analyzer (Abbott) falsely appear as extreme low value. Dilution should resolve the discrepency.
What are the common lab results concerning WM & MM? (3)
How can you differentiate WM from MM? (4)
- M spike in SPE
- High ESR, Rouleaux in FR, DAT+
- Low HB (Anaemia due to AIHA)
- WM is always Monoclonal IgM but MM can be Monoclonal IgG
- WM is Cryoglobulin + but MM is not (unless it is IgM MM)
- WM involves hepatosplenomegaly & lymphoadenopathy
- WM rarely present with lytic bone leision
Patient has motor regression, what would you consider?
His FT4 is low and TSH is high, why?
- Bone / Muscle wasting
PTH, vitamin D, CA PO4, CK - Infection
WBC, CRP - Heavy metal
Pb, Hg, Ar - Scurvy
Vitamin C, Celiac disease (absorption)
Unless patient presents with hypothyroidism, it is euthyroid sick syndrome in critical illness
When measuring HbA1c, CE result become falsely high but HPLC result is accurate, how is that possible when CE is theoretically more sensitive than HPLC? (1)
Regardless of detection method, why some Hb variant causes falsely low HbA1c? (1)
Would immunoturbidimetric method for HbA1c affected by Hb variant? (1)
CE is sensitive, so it separates Hb variants from HbA0 while HPLC can’t, the separated Hb variant is not counted as denominator, while Glycated Hb variant coelute with HbA1c & is counted as numerator, falsely elevating the HbA1c result.
some form of Hb variants are pathological, and patients who are homozygous for a Hb variant can become pathological. RBC life span decrease causes falsely low HbA1c.
Anti-HbA1c targets N-terminal glycated valine and a few AA next to it, so Hb variant won’t affect the measurement unless mutation of those sites are involved, although RBC life span alteration by some Hb variant causes HbA1c measured not reflecting glycemic control.