MLT GlobeChemistry: Tumor markers & iron studies
59 Chemistry MCQs on Tumor markers & iron studies with answers and explanations.
Which mineral is poorly supplied by milk, so infants fed only milk may become anaemic?
Milk is rich in calcium, phosphorus and potassium but contains little iron; prolonged exclusive milk feeding causes iron deficiency anaemia.
Which iron-storage protein releases iron most readily and is measured in serum to assess body iron stores?
Ferritin holds readily mobilised iron, and serum ferritin reflects stores. Hemosiderin is an insoluble, slowly released aggregate; transferrin transports iron rather than storing it.
Which tumour marker is mainly used to monitor recurrence of colorectal cancer after surgery?
CEA is not good for screening but is useful after resection: a rising level suggests recurrence. AFP is used for hepatocellular and germ cell tumours, CA-125 for ovarian cancer and PSA for prostate cancer.
Serum alpha-fetoprotein (AFP) is most useful as a marker for:
AFP is made by fetal liver and yolk sac, and it rises in hepatocellular carcinoma and nonseminomatous germ cell tumors. CA-125 is used for ovarian epithelial cancer.
A raised maternal serum AFP at 16–18 weeks of pregnancy is most associated with:
Fetal AFP leaks into amniotic fluid and maternal blood through an open neural tube defect. Down syndrome is usually associated with a LOW maternal AFP.
Which tumor marker is used mainly to monitor metastatic breast cancer?
CA 15-3 (a MUC1 antigen) is used to follow response and recurrence of breast cancer. It is not sensitive enough for early detection.
The main clinical use of most serum tumor markers is to:
Most markers lack the sensitivity and specificity for population screening. Serial measurements in a known patient are most useful for follow-up.
Serum calcitonin is a tumor marker for:
Medullary carcinoma arises from calcitonin-producing C cells. Papillary and follicular cancers are followed with thyroglobulin.
Which pattern fits iron deficiency anemia?
In iron deficiency, the liver makes more transferrin (high TIBC) while iron and stores (ferritin) fall. Low iron with low TIBC and high ferritin is typical of anemia of chronic disease.
A visibly hemolyzed sample is received for serum iron. What effect is expected?
Red cells contain large amounts of iron in hemoglobin, and hemolysis releases it into the sample. Hemolyzed samples should be rejected for iron studies.
In developing iron deficiency, which result becomes abnormal FIRST?
Storage iron is used first, so ferritin falls before transport iron (saturation) drops. Microcytosis and low hemoglobin appear only later.
Most hCG immunoassays use an antibody against the beta subunit because the alpha subunit:
hCG, LH, FSH and TSH share an almost identical alpha subunit; the beta subunit gives each hormone its specificity. Targeting beta-hCG avoids cross-reaction with the other glycoprotein hormones.
Which test is traditionally regarded as the gold standard for assessing body iron stores?
Perls Prussian blue staining of marrow directly shows storage iron in macrophages and sideroblasts. It is invasive, so serum ferritin is used in routine practice. Serum iron varies daily.
Dietary non-heme iron is absorbed in the duodenum mainly:
Duodenal cytochrome b reduces Fe3+ to Fe2+, which enters enterocytes via DMT1. Ferroportin exports iron from the cell into blood, where it is carried as Fe3+ on transferrin.
CA 19-9 is a tumor marker mainly associated with cancer of the:
CA 19-9 is used mainly for pancreatic (and biliary) cancer monitoring. It is not raised in people who lack the Lewis blood group antigen.
In plasma, iron is transported bound to which protein?
Transferrin carries iron in the blood to tissues such as the bone marrow. Ferritin and hemosiderin are storage forms and haptoglobin binds free hemoglobin.
Prostate-specific antigen (PSA) is produced by:
PSA is a serine protease made by prostatic epithelial cells, both normal and malignant, so it is prostate-specific but not cancer-specific.
Which insoluble iron storage compound is seen as blue granules in bone marrow macrophages with Prussian blue stain?
Hemosiderin is the insoluble, aggregated storage form of iron and stains blue with Perls' Prussian blue. Transferrin is a soluble plasma transport protein.
In women of reproductive age, the most common cause of iron deficiency is:
Chronic blood loss is the usual cause of iron deficiency in adults, and in women of reproductive age this is most often menstrual loss (along with pregnancy).
In an adult, a serum ferritin below about 15 ng/mL (15 µg/L) indicates:
Serum ferritin reflects body iron stores, and a value below about 15 µg/L is highly specific for iron deficiency. Inflammation raises ferritin rather than lowering it.