Plasma intestinal alkaline phosphatase isoenzymes in neonates with bowel necrosis.

Abstract

Aim-To determine if the intestinal isoenzymes of alkaline phosphatase (ALP) are biochemical markers of bowel necrosis in neonates. Methods-Plasma ALP isoenzymes were measured in 22 babies with bowel necrosis, histologically confirmed, and in 22 matched controls. The isoenzymes were also measured in 16 infants with signs of necrotising enterocolitis, who recovered without histological confirmation of bowel necrosis. The isoenzymes were separated by polyacrylamide gel electrophoresis. Auxiliary tests for identification included neuraminidase digestion and treatment with monoclonal and polyclonal antiplacental antibodies. Results-Intestinal ALP was detected in 16 infants with bowel necrosis-13 had fetal intestinal ALP (FI-ALP) and three had adult intestinal ALP (AI-ALP). FI-ALP was detected in nine of the controls. In the babies with bowel necrosis intestinal ALP was found over all gestations, but in the controls only in those less than 34 weeks. The percentages of total ALP activity due to intestinal ALP were significantly higher in those with bowel necrosis compared with matched controls (p = 0.028). In babies of all gestations diagnostic sensitivity for the presence of intestinal ALP as a marker of bowel necrosis was 73% and diagnostic specificity 590/o. In babies greater than 34 weeks' gestation, diagnostic sensitivity fell to 60% but the test became completely specific. In two babies FI-ALP increased from zeroltrace to high activity coincident with the episode of bowel necrosis. In 16 babies with signs of necrotising enterocolitis but unconfirmed bowel necrosis FI-ALP was detected in four. Conclusion-Intestinal ALP seems to be released into the circulation in some babies with bowel necrosis, but its detection does not have the diagnostic sensitivity and specificity to be a reliable biochemical marker of the condition.

Lactate dehydrogenase activity is increased in plasma of infants with advanced necrotizing enterocolitis

“…In neonates, the activity of various enzymes has been investigated as a possible marker of advanced NEC. Hexosaminidase, diamine oxidase, and ALP have shown not to be clinically useful [9,[26][27][28]. Our findings confirm that ALP, like other mucosal enzymes studied [9,[26][27][28], is a poor indicator of advanced NEC.…”

“…LDH, CK, and GOT are intracellular enzymes found in the seromuscular layer of the bowel wall, whereas, ALP is membrane-bound, mainly located in the mucosal layer [7,9]. When intestinal ischemic injury occurs, mucosal damage takes place, gradually progressing to necrosis of the villi and muscular layer.…”

Luminal calcium concentration controls intestinal calcium absorption by modification of intestinal alkaline phosphatase activity

“…A relationship with the process of fat absorption (4) and preservation of the normal homeostasis of the gut microbiota has been described previously (5) . IAP expression parallels that of other intestinal proteins involved in Ca absorption under vitamin D stimulation: Ca channel TRPV6, calbindin CD 9k , calcium sodium exchanger NCX 1 and Ca pump PMCAb1 (3,6,7) . Experiments carried out in vitro with purified IAP from the intestine of rats have demonstrated an interaction between Ca and IAP (8) .…”

“…Its contribution to total plasma alkaline phosphatase activity is less than 10 %, even under pathological conditions that increase this isoenzyme (1) . Its maximum expression is observed in the duodenum, with a gradual decrease throughout the intestine (2) , and its activity is higher in the tip of the villus than in the crypt, being a marker of mature enterocytes (3) .…”

Identification of a macro-alkaline phosphatase complex in a patient with inflammatory bowel disease

“…1 Raised serum intestinal ALP activity is of uncertain clinical significance, but has been reported in patients with liver cirrhosis, diabetes, chronic kidney disease, and in bowel ischaemia and infarction. 2 Occasionally, increased plasma ALP activity will be due to an immunoglobulin-bound form of ALP (macroALP); the kidneys have a role in clearing ALP from the circulation 3 and so macroALP complexes have reduced clearance due to their high molecular weight compared with unbound ALP. Several such macroALP complexes have been reported, but they have no known clinical significance.…”