Prevalence of low alkaline phosphatase activity in laboratory assessment: Is hypophosphatasia an underdiagnosed disease?

Abstract Background Tissue-nonspecific alkaline phosphatase (TNSALP) encoded by the ALPL gene is of particular importance for bone mineralization. Mutation in the ALPL gene can lead to persistent low ALP activity resulting in the rare disease Hypophosphatasia (HPP) that is characterized by disturbed bone and dental mineralization. While severe forms are extremely rare with an estimated prevalence of 1/100.000, recent studies suggest that moderate form caused by heterozygous mutations are much more frequent with an estimated prevalence of 1/508. The purpose of this study was to estimate the prevalence of low AP levels in the population based on laboratory measurements. Methods In this study, the prevalence of low AP activity and elevated pyridoxal-5-phosphate (PLP) levels was analyzed in 6.918.126 measurements from 2011 to 2016 at a single laboratory in northern Germany. Only laboratory values of subjects older than 18 years of age were included. Only the first measurement was included, all repeated values were excluded. Results In total, 8.46% of the measurements of a total of 6.918.126 values showed a value < 30 U/L. 0.59% of the subjects with an ALP activity below 30 U/L had an additional PLP measurement. Here, 6.09% showed elevated pyridoxal-5-phosphate (PLP) levels. This suggest that 0.52% (1:194) of subjects show laboratory signs of HPP. Conclusion These data support the genetic estimation that the prevalence of moderate forms of HPP may be significantly higher than expected. Based on these data, we recommend automatically measurement of PLP in the case of low ALP activity and a notification to the ordering physician that HPP should be included in the differential diagnosis and further exploration is recommended.

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Hypophosphatasia in children. Three faces of one disease

Russian Journal of Woman and Child Health ◽

10.32364/2618-8430-2020-3-2-136-141 ◽

2020 ◽

Vol 3 (2) ◽

pp. 136-141

Author(s):

S.A. Boykov ◽

◽

I.Yu. Chernyak ◽

N.S. Shatokhina ◽

E.Yu. Gurkina ◽

...

Keyword(s):

Alkaline Phosphatase ◽

Clinical Symptoms ◽

Bone Mineralization ◽

Case Reports ◽

Molecular Genetic ◽

Case Series ◽

Alp Activity ◽

Systemic Manifestations ◽

Molecular Genetic Test ◽

Reduced Mobility

Hypophosphatasia (HPP) is a rare multisystem inherited metabolic disorder caused by mutations in ALPL gene that encodes tissue nonspecific alkaline phosphatase responsible for bone mineralization. HPP is characterized by impaired bone mineralization, skeletal abnormalities, and systemic manifestations which result in significant morbidity and mortality. Clinical presentations of HPP vary greatly. Early (perinatal and infantile) HPP is characterized by the most severe symptoms, i.e., respiratory and neurological disorders are of crucial importance being the leading causes of death. Progressive skeletal impairment, rickets-like deformities, reduced mobility, and severe disability are typical of childhood-onset HPP. The biochemical hallmark of HPP is low alkaline phosphatase (ALP) activity. HPP diagnosis is verified by clinical symptoms in combination with persistently low ALP activity (adjusted for age and sex). Molecular genetic test to identify ALPL gene mutation is performed as needed. Three case reports addresses authors’ experience with the diagnosis and treatment for HPP.Keywords: hypophosphatasia, case series, alkaline phosphatase, impaired bone mineralization, asfotase alfa.For citation: Boykov S.A., Chernyak I.Yu., Shatokhina N.S. et al. Hypophosphatasia in children. Three faces of one disease. Russian Journal of Woman and Child Health. 2020;3(2):136–141. DOI: 10.32364/2618-8430-2020-3-2-136-141.

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P1237TISSUE-NONSPECIFIC ALKALINE PHOSPHATASE, A CULPRIT DURING ARTERIAL MEDIA CALCIFICATION BUT INDISPENSABLE DURING PHYSIOLOGICAL BONE FORMATION/-MINERALIZATION IN RATS

Nephrology Dialysis Transplantation ◽

10.1093/ndt/gfaa142.p1237 ◽

2020 ◽

Vol 35 (Supplement_3) ◽

Author(s):

Britt Opdebeeck ◽

José Millan Luis ◽

Anthony Pinkerton ◽

Anja Verhulst ◽

Patrick D'Haese ◽

...

Keyword(s):

Alkaline Phosphatase ◽

Bone Formation ◽

Vascular Calcification ◽

Rat Model ◽

Bone Mineralization ◽

Calcium Content ◽

Marker Genes ◽

Peripheral Arteries ◽

Calcium Phosphorus ◽

Chondrogenic Marker

Abstract Background and Aims Vascular media calcification is frequently seen in elderly and patients with chronic kidney disease (CKD), diabetes and osteoporosis. Pyrophosphate is a well-known calcification inhibitor that binds to nascent hydroxyapatite crystals and prevents further incorporation of inorganic phosphate into these crystals. However, the enzyme tissue-nonspecific alkaline phosphatase (TNAP), which is highly expressed in calcified arteries, degrades extracellular pyrophosphate into phosphate ions, by which pyrophosphate loses its ability to block vascular calcification. Here, we aimed to evaluate whether a TNAP inhibitor is able to prevent the development of arterial calcification in a rat model of warfarin-induced vascular calcification. Method To induce vascular calcification, rats received a diet containing 0.30% warfarin and 0.15% vitamin K1 throughout the entire study and were subjected to the following daily treatments: (i) vehicle (n=10) or (ii) 10 mg/kg/day TNAP-inhibitor (n=10) administered via an intraperitoneal catheter from start of the study until sacrifice at week 7. Calcium, phosphorus and parathyroid hormone (PTH) levels were determined in serum samples as these are important determinants of vascular calcification. As TNAP is also expressed in the liver, serum alanine aminotransferase (ALT) and aspartate (AST) levels were analyzed. At sacrifice, vascular calcification was evaluated by measurement of the total calcium content in the arteries and quantification of the area % calcification on Von Kossa stained sections of the aorta. The mRNA expression of osteo/chondrogenic marker genes (runx2, TNAP, SOX9, collagen 1 and collagen 2) was analyzed in the aorta by qPCR to verify whether vascular smooth muscle cells underwent reprogramming towards bone-like cells. Bone histomorphometry was performed on the left tibia to measure static and dynamic bone parameters as TNAP also regulates physiological bone mineralization. Results No differences in serum calcium, phosphorus and PTH levels was observed between both study groups. Warfarin exposure resulted in distinct calcification in the aorta and peripheral arteries. Daily dosing with the TNAP inhibitor (10 mg/kg/day) for 7 weeks significantly reduced vascular calcification as indicated by a significant decrease in calcium content in the aorta (vehicle 3.84±0.64 mg calcium/g wet tissue vs TNAP inhibitor 0.70±0.23 mg calcium/g wet tissue) and peripheral arteries and a distinct reduction in area % calcification on Von Kossa stained aortic sections as compared to vehicle condition. The inhibitory effects of SBI-425 on vascular calcification were without altering serum liver markers ALT and AST levels. Furthermore, TNAP-inhibitor SBI-425 did not modulate the mRNA expression of osteo/chondrogenic marker genes runx2, TNAP, SOX9, collagen 1 and 2. Dosing with SBI-425 resulted in decreased bone formation rate and mineral apposition rate, and increased osteoid maturation time and this without significant changes in osteoclast- and eroded perimeter. Conclusion Dosing with TNAP inhibitor SBI-425 significantly reduced the calcification in the aorta and peripheral arteries of a rat model of warfarin-induced vascular calcification and this without affecting liver function. However, suppression of TNAP activity should be limited in order to maintain adequate physiological bone mineralization.

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Hypophosphatasia: A Unique Disorder of Bone Mineralization

International Journal of Molecular Sciences ◽

10.3390/ijms22094303 ◽

2021 ◽

Vol 22 (9) ◽

pp. 4303

Author(s):

Juan Miguel Villa-Suárez ◽

Cristina García-Fontana ◽

Francisco Andújar-Vera ◽

Sheila González-Salvatierra ◽

Tomás de Haro-Muñoz ◽

...

Keyword(s):

Alkaline Phosphatase ◽

Genetic Disease ◽

Therapeutic Strategy ◽

Pediatric Patients ◽

Bone Mineralization ◽

Clinical Manifestations ◽

Allelic Heterogeneity ◽

Specific Enzyme ◽

Inorganic Pyrophosphate ◽

Enzyme Replacement

Hypophosphatasia (HPP) is a rare genetic disease characterized by a decrease in the activity of tissue non-specific alkaline phosphatase (TNSALP). TNSALP is encoded by the ALPL gene, which is abundantly expressed in the skeleton, liver, kidney, and developing teeth. HPP exhibits high clinical variability largely due to the high allelic heterogeneity of the ALPL gene. HPP is characterized by multisystemic complications, although the most common clinical manifestations are those that occur in the skeleton, muscles, and teeth. These complications are mainly due to the accumulation of inorganic pyrophosphate (PPi) and pyridoxal-5′-phosphate (PLP). It has been observed that the prevalence of mild forms of the disease is more than 40 times the prevalence of severe forms. Patients with HPP present at least one mutation in the ALPL gene. However, it is known that there are other causes that lead to decreased alkaline phosphatase (ALP) levels without mutations in the ALPL gene. Although the phenotype can be correlated with the genotype in HPP, the prediction of the phenotype from the genotype cannot be made with complete certainty. The availability of a specific enzyme replacement therapy for HPP undoubtedly represents an advance in therapeutic strategy, especially in severe forms of the disease in pediatric patients.

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Relationship between Serum Alkaline Phosphatase and Low Muscle Mass Index Among Korean Adults: A Nationwide Population-Based Study

Biomolecules ◽

10.3390/biom11060842 ◽

2021 ◽

Vol 11 (6) ◽

pp. 842

Author(s):

Jun-Hyuk Lee ◽

A-Ra Cho ◽

Yong-Jae Lee

Keyword(s):

Skeletal Muscle ◽

Alkaline Phosphatase ◽

Muscle Mass ◽

Skeletal Muscle Mass ◽

Serum Alkaline Phosphatase ◽

Inflammatory Marker ◽

Characteristic Curve ◽

Population Based ◽

Nutrition Survey ◽

The Difference

Sarcopenia has attracted interest due to its impact on various health problems. Chronic inflammation is an important contributor to sarcopenia. Thus, we aimed to investigate the association between serum alkaline phosphatase (ALP), which is a novel inflammatory marker, and muscle mass. This study included 15,579 adults from the 2008–2011 Korea National Health and Nutrition Survey. Low skeletal muscle mass index (LSMI) was defined as body mass index-adjusted appendicular skeletal muscle mass less than 0.789 for men and 0.512 for women. Multiple logistic regression revealed that the highest ALP tertile was significantly associated with LSMI compared with the lowest ALP tertile in both men [Odds ratio (OR): 1.41; 95% confidence interval (CI): 1.04–1.91] and women (OR: 1.45; 95% CI: 1.00–2.10) after adjusting for other confounders. On the receiver operating characteristic curve analysis, the predictive power was significantly higher for ALP levels than for white blood cell count in women (p < 0.001), whereas the difference was not significant in men (p = 0.515). Our findings suggest the potential use of serum ALP as an inflammatory marker and a predictor of sarcopenia.

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Evaluation of Spectrophotometric and Fluorometric Methods for Alkaline Phosphatase Activity Determination in Ewe's Milk

Journal of Food Protection ◽

10.4315/0362-028x-63.9.1258 ◽

2000 ◽

Vol 63 (9) ◽

pp. 1258-1261 ◽

Cited By ~ 15

Author(s):

M. F. SCINTU ◽

E. DAGA ◽

A. LEDDA

Keyword(s):

Alkaline Phosphatase ◽

Standard Deviation ◽

Raw Milk ◽

Cow’S Milk ◽

Official Method ◽

Cow's Milk ◽

Alp Activity ◽

Relative Standard ◽

Ewe's Milk ◽

European Method

The alkaline phosphatase (ALP) activity test has been used since 1935 to assess the effectiveness of pasteurization. Different analytical methods exist for detecting ALP in milk. Unfortunately, there is little information about ALP activity in ewe's milk. The aim of this study was to assess and compare the official European method (spectrophotometric method) and the Fluorophos method (fluorometric method) regarding their use in ewe's milk. Bulk ewe's milk samples were taken from a flock and from three different dairies. A portion of the original sample was pasteurized at 63°C for 30 min in a circulating bath; another portion was heated to and kept at 95°C for about 2 min, and 0.1% (vol/vol) of raw milk was added. The samples obtained were analyzed in duplicate using the spectrophotometric and fluorometric methods. The relation between ALP activity determined by the two methods was characterized by the following equation: Y = 1.34 + 0.0039X (where Y = ALP in μg of phenol per ml of milk and X = ALP in mU/liter; R2 = 91.5%). Precision parameters (repeatability [r], standard deviation of repeatability [sr], and relative standard deviation of repeatability [RSDr]) for both methods were calculated. The values of RSDr for the Fluorophos method were 4.30 for pasteurized milk and 2.96 for 0.1% raw milk, close to the value indicated by Rocco in whole cow's milk (RSDr = 4.4). The repeatability for the official method (r = 2.16) was close to that indicated for whole cow's milk (r = 2).

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Residual Alkaline Phosphatase Activity in Milks Subjected to Various Time-Temperature Treatments

Journal of Food Protection ◽

10.4315/0362-028x-60.5.525 ◽

1997 ◽

Vol 60 (5) ◽

pp. 525-530 ◽

Cited By ~ 22

Author(s):

C. J. PAINTER ◽

R. L. BRADLEY

Keyword(s):

Alkaline Phosphatase ◽

Activity Levels ◽

Milk Product ◽

Milk Products ◽

Alp Activity ◽

High Temperature Short Time ◽

Thermally Processed ◽

Long Time ◽

The Mean ◽

Fluid Milk

Milk is routinely tested for proper pasteurization. The Scharer and Fluorophos methods, among others, test for residual alkaline phosphatase (ALP) activity to assure proper pasteurization. Until recently there were no tests available to accurately detect residual ALP activity levels below the U.S. legal limit of 1 μg of phenol or 350 mU of ALP per liter of milk. The new Fluorophos method can detect accurately residual ALP activity levels as low as 10 mU/liter. The Fluorophos method was used to investigate residual ALP activity levels in several fluid milk products. The milk products were thermally processed under various time and temperature protocols below, at, and above current U.S. Food and Drug Administration-mandated heat treatments for fluid milk and milk products. The data established values for residual ALP activity in milks pasteurized under high-temperature short-time (HTST) and low-temperature long-time (LTLT) treatments. The mean ALP activities for whole, 2% lowfat, 1% lowfat, skim, half and half, and chocolate-flavored milks thermally processed at the legal minimum HTST pasteurization treatment are 169.7 ± 12.3, 145.2 ± 9.3, 98.6 ± 8.9, 72.5 ± 4.2, 38.4 ± 4.6 and 157.3 ± 6.5 mU/liter, respectively. The mean ALP activities generated at the legal minimum LTLT pasteurization treatment are 81.8 ± 4.8, 66.4 ± 5.9, 56.4 ± 2.1, 39.1 ± 3.9, 35.0 ± 1.2 and 91.3 ± 7.7 mU/liter, respectively. The values for all milks pasteurized at the legal minimum heat treatment were significantly below the current legal cutoff for residual ALP activity of 350 mU/liter of milk or milk product.

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Alkaline Phosphatase Isoenzyme Patterns in Malignant Disease

Clinical Chemistry ◽

10.1093/clinchem/38.12.2546 ◽

1992 ◽

Vol 38 (12) ◽

pp. 2546-2551 ◽

Cited By ~ 20

Author(s):

V O Van Hoof ◽

A T Van Oosterom ◽

L G Lepoutre ◽

M E De Broe

Keyword(s):

Alkaline Phosphatase ◽

Liver Disease ◽

Liver Metastasis ◽

Bone Metastasis ◽

Positive Predictive Value ◽

Bone Disease ◽

Predictive Value ◽

Malignant Disease ◽

Alp Activity ◽

Isoenzyme Patterns

Abstract Early treatment of patients with malignant disease and liver or bone metastasis may increase their survival time. We have used the activity patterns of liver and bone isoenzymes of alkaline phosphatase (ALP), separated by agarose gel electrophoresis, to detect early metastasis. We studied ALP isoenzyme patterns in a background population of 101 patients with no evidence of any disease that might influence this pattern; a healthy reference population (n = 330); and the following three groups of patients: 143 with malignant disease, 47 with nonmalignant liver disease, and 22 with nonmalignant bone disease. Cutoff and predictive values of liver ALP, high-molecular-mass (high-M(r)) ALP, and bone ALP were established for detecting liver and bone metastasis. The positive predictive value of liver and high-M(r) ALP was higher than that of total ALP in detecting liver metastasis, but liver and high-M(r) ALP did not enable us to differentiate between malignant and nonmalignant liver disease. Total ALP activity was of slightly more value than liver and high-M(r) ALP in enabling us to rule out liver metastasis. From bone ALP activity we could not distinguish between nonmalignant bone disease and bone metastasis. The negative predictive value of bone ALP in the diagnosis of bone metastasis was low, but its positive predictive value was high and superior to that of total ALP.

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Non-Hepatic Alkaline Phosphatase, hs-CRP and Progression of Vertebral Fracture in Patients with Rheumatoid Arthritis: A Population-Based Longitudinal Study

Journal of Clinical Medicine ◽

10.3390/jcm7110439 ◽

2018 ◽

Vol 7 (11) ◽

pp. 439 ◽

Cited By ~ 6

Author(s):

Jih-Chen Yeh ◽

Chang-Chin Wu ◽

Cheuk-Sing Choy ◽

Shu-Wei Chang ◽

Jian-Chiun Liou ◽

...

Keyword(s):

Rheumatoid Arthritis ◽

Alkaline Phosphatase ◽

Cox Regression ◽

High Sensitivity ◽

Population Based ◽

Reactive Protein ◽

Prognostic Assessment ◽

Product Term ◽

Hs Crp ◽

Stratified Analysis

Background: Interactions and early warning effects of non-hepatic alkaline phosphatase (NHALP) and high-sensitivity C-reactive protein (hs-CRP) on the progression of vertebral fractures (VFs) in patients with rheumatoid arthritis (RA) remain unclear. We aim to explore whether serum concentrations of NHALP and hs-CRP could serve as a promising dual biomarker for prognostic assessment of VF progression. Methods: Unadjusted and adjusted hazard ratios (aHRs) of VF progression were calculated for different categories of serum NHALP and hs-CRP using the Cox regression model in RA patients. The modification effect between serum NHALP and hs-CRP on VF progression was determined using an interaction product term. Results: During 4489 person-years of follow-up, higher NHALP (>125 U/L) and hs-CRP (>3.0 mg/L) were robustly associated with incremental risks of VF progression in RA patients (aHR: 2.2 (95% confidence intervals (CIs): 1.2–3.9) and 2.0 (95% CI: 1.3–3.3) compared to the lowest HR category, respectively). The interaction between NHALP and hs-CRP on VF progression was statistically significant (p < 0.05). In the stratified analysis, patients with combined highest NHALP and hs-CRP had the greatest risk of VF progression (aHR: 4.9 (95% CI: 2.5–9.6)) compared to the lowest HR group (NHALP < 90 U/L and hs-CRP < 1 mg/L). Conclusions: In light of underdiagnoses of VFs and misleading diagnosis by single test, NHALP and hs-CRP could serve as compensatory biomarkers to predict subclinical VF progression in RA patients.

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Development of Ca2+ homeostasis in epithelial cells from embryonic and neonatal intestine

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.1992.263.3.g371 ◽

1992 ◽

Vol 263 (3) ◽

pp. G371-G379

Author(s):

B. L. Black ◽

J. O. Rogers

Keyword(s):

Alkaline Phosphatase ◽

Epithelial Cell ◽

Epithelial Cells ◽

Fluorescent Probe ◽

Cell Suspensions ◽

Fura 2 ◽

Alp Activity ◽

High Viability ◽

Cytoplasmic Compartment ◽

Highly Correlated

The fluorescent probe fura-2 was used to assay Ca2+ levels in epithelial cell suspensions from embryonic and neonatal chick duodenum. Cell preparations maintained high viability, completely hydrolyzed fura-2/AM to fura-2, retained 92% of cellular fura-2 within the cytoplasmic compartment, and gave low autofluorescence values during assay. Fura-2 leakage from loaded cells occurred at all ages, but could be corrected for in subsequent calculations of cellular Ca2+. Cytoplasmic Ca2+ concentration was 76-80 nM in cells from 14- to 16-day embryonic intestine, rose significantly to 92-98 nM at 17-20 days, and reached 209 nM at 1-day post-hatch when assayed in buffers containing 1.3 mM Ca2+. The developmental rise in cytoplasmic Ca2+ was accompanied by an enhanced ability of cells to maintain a constant Ca2+ concentration at increased levels of extracellular Ca2+ and by a highly correlated rise in alkaline phosphatase (ALP) activity. Epithelial Ca2+ subsequently decreased to the "adult" value of 133-142 nM and was constant along the crypt-villus axis of neonatal intestine. These results verify that fura-2 can be used to compare baseline cytoplasmic Ca2+ values of epithelial cells from developing intestine, reveal that significant changes in Ca2+ homeostasis occur during ontogeny, and suggest that epithelial Ca2+ may modulate ALP activity during the differentiation of embryonic enterocytes.

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Interleukin-1β enhances retinoic acid-mediated expression of bone-type alkaline phosphatase in rat IEC-6 cells

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.2001.280.3.g510 ◽

2001 ◽

Vol 280 (3) ◽

pp. G510-G517 ◽

Cited By ~ 8

Author(s):

Takeshi Nikawa ◽

Madoka Ikemoto ◽

Kaori Tokuoka ◽

Shigetada Teshima ◽

David H. Alpers ◽

...

Keyword(s):

Alkaline Phosphatase ◽

Retinoic Acid ◽

Retinoic Acid Receptor ◽

Transcript Level ◽

Intestinal Epithelial ◽

Alp Activity ◽

Kinase C ◽

Fetal Rat ◽

Epidermal Growth

We previously showed that vitamin A upregulated the expression of bone-type alkaline phosphatase (ALP) in fetal rat small intestine and rat intestinal IEC-6 cells. In this study, we examined interactions between retinoic acid (RA) and several growth factors/cytokines on the isozyme expression in IEC-6 cells. Epidermal growth factor and interleukins (ILs)-2, -4, -5, and -6 completely blocked the RA-mediated increase in ALP activity. In contrast, IL-1β markedly increased the activity, protein, and mRNA of the bone-type ALP only when RA was present. IL-1β and/or RA did not change the type 1 IL-1 receptor transcript level, whereas IL-1β enhanced the RA-induced expressions of retinoic acid receptor-β (RAR-β) and retinoid X receptor-β (RXR-β) mRNAs and RA-mediated RXR response element binding. The synergism of IL-1β and RA on ALP activity was completely blocked by protein kinase C (PKC) inhibitors. Our results suggest that IL-1β may modify the ALP isozyme expression in small intestinal epithelial cells by stimulating PKC-dependent, RAR-β- and/or RXR-β-mediated signaling pathways.

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