Clinical Enzymology: Alkaline Phosphatase (ALP)
45 Questions
0 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the primary reason for the higher alkaline phosphatase (ALP) levels observed in boys during childhood?

  • Bone isoenzyme activity (correct)
  • Higher bone density
  • Increased liver isoenzyme activity
  • Higher levels of kidney isoenzyme

    • What effect does pregnancy have on alkaline phosphatase (ALP) levels?

  • Causes a two- to threefold increase primarily due to the placental isoenzyme (correct)
  • Increases ALP only in the liver isoenzyme
  • No significant effect on ALP levels during pregnancy
  • Decreases ALP slightly due to hormonal changes

    • Which factor is associated with an increase in alkaline phosphatase (ALP) levels?

  • High body mass index (correct)
  • Blood transfusion
  • Oral contraceptives
  • Cardiopulmonary bypass

    • What is the effect of fibric acid derivatives on alkaline phosphatase (ALP)?

    <p>Decrease total ALP by 25% and liver isoenzyme by 40%</p> Signup and view all the answers

    How does smoking influence alkaline phosphatase (ALP) levels?

    <p>Leads to a 10% average increase in total ALP levels</p> Signup and view all the answers

    What is the primary source of GGT found in serum?

    <p>Hepatobiliary system</p> Signup and view all the answers

    In cases of biliary obstruction, how much can GGT levels increase compared to the upper reference limit (URL)?

    <p>5 to 30 times</p> Signup and view all the answers

    What condition is NOT associated with increased GGT levels?

    <p>Hyperthyroidism</p> Signup and view all the answers

    What is the correlation between GGT levels and body weight?

    <p>GGT levels are higher in individuals with increased body weight</p> Signup and view all the answers

    Which factor does NOT contribute to increased GGT levels?

    <p>Increased physical activity</p> Signup and view all the answers

    What is the primary role of alkaline phosphatase (ALP) in cells?

    <p>Cleavage of phosphate-containing compounds</p> Signup and view all the answers

    What is the significance of GGT as a biochemical marker?

    <p>Sensitive but not very specific for hepatobiliary disease</p> Signup and view all the answers

    Which enzyme isoform is primarily produced by osteoblasts?

    <p>Bone ALP</p> Signup and view all the answers

    What increase in GGT activity is observed in infectious hepatitis?

    <p>Moderate increase (two to five times the URL)</p> Signup and view all the answers

    Which of the following ions acts as an inhibitor of ALP activity?

    <p>Phosphate ions</p> Signup and view all the answers

    In what situation might GGT levels be transiently increased?

    <p>Drug intoxication</p> Signup and view all the answers

    Where is alkaline phosphatase predominantly located in hepatocytes?

    <p>Canalicular surface</p> Signup and view all the answers

    Which of the following genes codes for the intestinal isoform of ALP?

    <p>A gene on chromosome 2</p> Signup and view all the answers

    What component is a constituent metal ion of ALP?

    <p>Zn2+</p> Signup and view all the answers

    What physiological function does the tissue-nonspecific isozyme of ALP primarily serve?

    <p>Facilitating the movement of substances across membranes</p> Signup and view all the answers

    Which type of ALP is produced following the ingestion of fatty foods?

    <p>Intestinal ALP</p> Signup and view all the answers

    What is the half-life of prostatic ACP?

    <p>1 to 3 hours</p> Signup and view all the answers

    Which factor can lead to falsely low values for tartrate-resistant ACP (TRAP) activity?

    <p>High bilirubin levels</p> Signup and view all the answers

    Why has the measurement of ACP become less popular for prostate cancer diagnosis?

    <p>PSA has become the major serum test</p> Signup and view all the answers

    What condition is NOT associated with elevated levels of ACP?

    <p>Chronic kidney disease</p> Signup and view all the answers

    Which of the following best describes the reference range for serum ACP?

    <p>≤ 2 ng/mL</p> Signup and view all the answers

    What is the optimal pH range for NTP activity?

    <p>6.6 to 7.0</p> Signup and view all the answers

    What is a significant drawback of using ACP for prostate cancer screening?

    <p>Sensitivity is inferior to PSA</p> Signup and view all the answers

    In which condition is serum NTP activity likely to be increased?

    <p>Biliary cirrhosis</p> Signup and view all the answers

    What is the primary method used to separate isoenzymes of ACP?

    <p>Electrophoresis</p> Signup and view all the answers

    Which statement is true regarding NTP and ALP activities?

    <p>Increased NTP activity often indicates liver disease even with normal ALP.</p> Signup and view all the answers

    In which demographic does total and tartrate-resistant ACP levels typically increase?

    <p>Women after menopause</p> Signup and view all the answers

    What are the normal reference intervals for NTP activity at 37°C?

    <p>3 to 9 U/L</p> Signup and view all the answers

    What is the expected change in NTP activity in cases of infectious hepatitis?

    <p>Moderately increased</p> Signup and view all the answers

    What is the primary clinical significance of measuring NTP activity?

    <p>Identifying hepatobiliary diseases</p> Signup and view all the answers

    Which of these conditions might lead to increased serum NTP activity?

    <p>Cholestasis from chlorpromazine</p> Signup and view all the answers

    How does NTP activity correlate with serum ALP in liver diseases?

    <p>They may dissociate in liver diseases.</p> Signup and view all the answers

    What is the primary source of increased alkaline phosphatase (ALP) activity in serum during hepatobiliary disease?

    <p>Hepatocytes</p> Signup and view all the answers

    Which isoenzyme of alkaline phosphatase has the shortest half-life?

    <p>Intestinal isoenzyme</p> Signup and view all the answers

    What factor is responsible for the release of alkaline phosphatase from cells during liver injury?

    <p>Increased cell membrane fragmentation</p> Signup and view all the answers

    Which condition is likely to cause a higher ALP activity due to extrahepatic obstruction?

    <p>Obstructive jaundice from a gallstone</p> Signup and view all the answers

    What percentage of day-to-day variability is associated with the bone isoenzyme of alkaline phosphatase?

    <p>20% to 25%</p> Signup and view all the answers

    Which forms of alkaline phosphatase are typically found in normal serum?

    <p>Single form of ALP from liver or bone</p> Signup and view all the answers

    What is the approximate half-life of the liver isoenzyme of alkaline phosphatase?

    <p>3 days</p> Signup and view all the answers

    In conditions of hepatobiliary disease, what types of ALP can be found in plasma?

    <p>Both normal product and high molecular weight forms</p> Signup and view all the answers

    Study Notes

    Clinical Enzymology

    • This topic covers clinical enzymology, a subfield of clinical biochemistry.

    Alkaline Phosphatase (ALP)

    • ALP is a type of hydrolase enzyme.
    • Multiple genes code for different ALP isoforms.
    • Their physiological role isn't fully understood.
    • Tissue-nonspecific isozyme is abundant in the kidney, liver, and bone.
    • Post-translational modifications lead to different carbohydrate side chains in various tissues.
    • Two other genes on chromosome 2 code for placental and intestinal ALP isoforms.
    • Another gene codes for a germ cell/placental-like isoenzyme with similar properties to the placental isoenzyme.
    • The enzyme is primarily bound to cell membranes, involved in phosphate cleavage, and facilitating substance transport.
    • Hepatocytes produce ALP attached to the canalicular surface.
    • Osteoblasts produce bone ALP, involved in pyrophosphate cleavage (an inhibitor of bone mineralization).
    • Intestinal epithelial cells produce intestinal ALP, released after fatty food ingestion.
    • Divalent ions like Mg2+, Co2+, and Mn2+ are ALP activators.
    • Zn2+ is a constituent metal ion.
    • Ions like phosphate, borate, oxalate, and cyanide are potent inhibitors.
    • Diverse release mechanisms of ALP from cells result in various plasma forms.
    • In liver injury, ALP synthesis increases.
    • Bile acids dissolve canalicular membrane fragments.
    • Normal serum typically has a single liver or bone form of ALP.
    • Hepatobiliary disease shows both normal and attached membrane form ALP.
    • Intestinal isoenzyme is released into duodenal fluid and lymphatic fluid after meals.
    • ALP isoenzyme half-lives differ: intestine(minutes), bone(1 day), liver(3 days), and placenta(7 days).
    • Day-to-day variation in total ALP is 5-10%, while bone isoenzyme shows 20% variability.
    • Different locations of ALP in the body: liver (low in liver, high in biliary tree), intestine (renal tubular cells), placenta, and bone (osteoblast).
    • ALP increases in serum are from liver or bone.
    • Hepatobiliary disease and bone disease are ALP activity sources.
    • Obstruction of biliary tracts causes ALP synthesis to increase by 10-12 times.
    • Other sources of elevated serum ALP include advanced primary liver cancer, widespread secondary hepatic metastases, liver disease primarily affecting parenchymal cells, and primary biliary cirrhosis.
    • Increased ALP is observed in pregnancy (up to two to three times URL).
    • Benign transient ALP increases can be in infants and children.
    • Carcinoplacental isoenzymes (like Regan isoenzyme) result from placental ALP gene de-repression.
    • Different tumor types produce modified non-placental isoenzymes (like Kasahara isoenzyme).
    • Increased osteoblastic activity (Paget disease, osteosarcoma, bone metastases, metabolic bone disease) elevates bone isoenzyme.

    5'-Nucleotidase (5NT)

    • 5' -Nucleotidase an enzyme acts only on nucleoside-5'-phosphates, releasing inorganic phosphate.
    • Widely distributed in tissues, localized in cell membranes,
    • pH optimum is between 6.6 and 7.0.
    • Serum NTP activity appears to reflect hepatobiliary disease with high specificity (increases 3-6 fold).
    • Elevated NTP is due to extrahepatic or intrahepatic conditions interfering with bile secretion.
    • Serum NTP activity may be normal in approximately half of individuals with elevated liver ALP.
    • Increased NTP in normal liver ALP suggests liver disease.

    ɣ-Glutamyltransferase (GGT)

    • GGT catalyzes the transfer of the γ-glutamyl group from peptides to acceptors.
    • It acts only on peptides with a terminal glutamate residue.
    • Found high in proximal renal tubule, liver, pancreas, and intestine.
    • The enzyme is cytoplasmic and present in cell membranes, potentially transporting amino acids/peptides.
    • Crucial for maintaining adequate intracellular glutathione (antioxidant).
    • Serum GGT activity comes mainly from the liver, commonly rising in various forms of liver disease.
    • Elevated in most subjects with liver illness, regardless of the cause.
    • In biliary obstruction, GGT increases 5-30 times its upper reference limit (URL).
    • Increased GGT is also found with increased body mass index, alcohol use, pregnancy, and anticonvulsant treatment.
    • GGT activities show an independent prognostic value for cardiovascular morbidity and mortality, and have redox/pro-oxidant reactions in cell.

    Acid Phosphatase (ACP)

    • ACP is a hydrolase enzyme breaking down phosphate monoesters.
    • All ACPs show optimal activity below pH 7.0.
    • High concentration locations include prostate, liver, spleen, erythrocytes, and bone.
    • Multiple forms with various molecular weights and tartrate sensitivities exist (e.g., lysosomal, prostatic, erythrocytic, macrophage, osteoclastic), crucial in bone remodeling.
    • Serum ACP concentration is low, and erythrocyte ACP is differentiated from other types by inhibiting it with substances.
    • A specific isoform of tartrate-resistant acid phosphatase (TRAP or TRAPase) is commonly found in osteoclasts and used to measure bone remodeling.
    • A type of TRAP called TRAP-5b is of crucial interest, acting in bone remodeling.
    • Serum ACP values depend on factors like age, gender, and hormone levels.
    • Total ACP and tartrate-resistant ACP are higher in children.
    • In women, total and tartrate-resistant activities increase after menopause.
    • Prostatic ACP has a 1-3 hour half-life.
    • ACP assays rely on hydrolysis to produce a measurable compound.
    • Elevated ACP associated with prostate disease, though PSA is the primary test for it.
    • Other potential causes include prostatic hyperplasia, malignancy, and urinary issues.
    • Clinical conditions like prostatic massage, inflammation, infarction, and procedures like biopsies can lead to temporary increases.
    • In suspected rape cases, vaginal fluid ACP provides a possible indicator.

    Studying That Suits You

    Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

    Quiz Team

    Related Documents

    Clinical Enzymology 2 PDF

    Description

    This quiz focuses on alkaline phosphatase (ALP), a crucial hydrolase enzyme in clinical enzymology. Explore its various isoforms, genetic coding, physiological roles, and involvement in different tissues such as the liver, kidneys, and bone. Test your knowledge on the diverse functions and characteristics of ALP and its importance in clinical biochemistry.

    More Like This

    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser