Objective: The aim of the study was the assessment of calcium-phosphorus-magnesium homeostasis in pregnant women after renal transplantation.
Methods: The study covered 64 pregnant women in the third trimester of gestation including: 33 women after renal transplantation (the study group) and 31 healthy pregnant women (the control group). Women from both groups were at the similar age: 30.8+/-4.7 vs. 31.3+/-5.0 years (NS) and at the same gestational age 34.8+/-2.4 vs. 35.3+/-2.6 weeks (NS). The mean body mass index (BMI) in the women from the study group before pregnancy was 21.49+/-2.81 vs. 22.1+/-3.02 in the control group (NS), BMI before delivery was 25.43+/-3.05 vs. 26.0+/-3.35 (NS), the percentage of the BMI increase during pregnancy was 18.7+/-7.68 vs. 17.65+/-7.13 (NS) and BMI increase during gestation was 3.93+/-1.56 vs. 3.90+/-1.54, respectively (NS). Arterial blood pressure at the time of blood samples collection for biochemical tests was 151.4+/-26.8/92.5+/-16.9 in women from the study group comparing to 115.0+/-6.0/68.0+/-7.0 mmHg (P<0.001) in the patients from the control group. The maximal blood pressure during pregnancy was 169.2+/-20.7/102.7+/-14.0 vs. 118.0+/-7.0/70.0+/-8.0 mmHg (P<0.001), respectively. We estimated serum levels of: total Ca, ionized Ca(2+), inorganic phosphorus (P(i)), Mg, total protein, albumin and blood morphology. Moreover, urine levels of Ca, P(i), Mg and protein were assessed.
Results: The pregnant women after renal transplantation presented increases in serum concentrations of total Ca (2.54+/-0.20 vs. 2.16+/-0.10 mmol/l; P<0.001) and ionized Ca(2+) (1.322+/-0.104 vs. 1.12+/-0.07 mmol/l; P<0.001) and the decrease in P(i) level (1.013+/-0.211 vs. 1.10+/-0.16 mmol/l; P<0.05), total protein (59.3+/-7.0 vs. 65+/-5 g/l; P<0.001) and albumin (461.6+/-65.65 vs. 493.2+/-59 micromol/l; P<0.05). Moreover, in the study group drop in red blood cells count to 3.71+/-0.56 vs. 4.01+/-0.35 x 10(12)/l (P<0.02) in the control group was detected. Despite increased volume of 24-h urine collection in the kidney recipients we observed significantly decreased urine 24-h calcium excretion 2.47+/-0.92 vs. 6.72+/-3.49 mmol (P<0.001) and simultaneous increase in urine Mg excretion 3.422+/-1.025 vs. 2.18+/-0.52 mmol/24 h (P<0.001). There was no difference in urine 24-h P(i) excretion between the study and the control group. The pregnant renal transplant recipients presented proteinuria of 1.19+/-1.9 g/24 h.
Conclusions: Women after kidney grafting present vital aberrations in calcium-phosphorus-magnesium homeostasis during pregnancy. The most significant changes are associated with calcium metabolism (high increase in serum Ca levels and impairment of renal elimination of calcium). The observed changes may be influenced by the doses of immunosuppressive agents and disturbed renal function.