Table 3.

Observational studies on intestinal alkaline phosphatase (IAP) and chronic kidney disease

References	Patients	Results
Walker (1974) [136]	29 HS 44 HD patients 556 other patients (OP)	IAP bands on electrophoresis (%) HS: 48%, HD patients: 50%, OP: 9% Total AP bands on electrophoresis (%) HS: 5 to 16 IU/L, HD patients: 9 to 57 IU/L, OP: 16 to 542 IU/L
De Broe et al. (1974) [137]	111 HD patients	↑ IAP in 29.7% of the patients
Skillen (1977) [138]	100 non-dialyzed patients 114 HD patients	↑ IAP in 15% in HD patients and 10% of non-dialyzed patients. IAP was detected in 36% of those patients with normal serum AP activity
Stĕpán et al. (1984) [139]	21 non-dialyzed patients 52 HD patients	Patients without hepatopathy: IAP activity was inversely correlated with Ca serum levels and positively correlated with iPTH levels Patients with hepatopathy: No correlation between iPTH and IAP, IAP in serum was influenced by blood group, liver ALP activity in serum and serum GMT activity.
Alpers et al. (1988) [127]	42 HD patients with ↑ total ALP serum levels	Before HD session: 62% had detectable IAP in plasma (222 IU/L (125–625) IAP measuring by rocket was 17.9 ± 2.3%, and by electrophoresis was 10.2 ± 1.9%. After HD session: IAP of 12.8 ± 3.1% (by rocket), and 9.5 ± 2.1% (by electrophoresis
Tibi et al. (1991) [140]	75 HD patients	↑ total ALP activity in 28 patients; IAP > 23 UI/L in 8 patients (responsible for increase in total AP in only one patient)
Tsumura et al. (2001) [36]	108 CKD non-dialyzed patients 106 healthy subjects	With polyacrylamide gel electrophoresis analysis, authors found atypical AP in serum and urine in patients, which could be an intestinal-type AP
Zetterberg et al. (2005) [37]	2 PD patients	↑ serum total AP and IAP activity

HS, healthy subjects; HD, hemodialysis; CrCl, creatinine clearance; PD, peritoneal dialysis; iPTH, intact parathyroid hormone; AP, alkaline phosphatase