China
Africa
Explore chapters and articles related to this topic
Renal Disease
Published in Praveen S. Goday, Cassandra L. S. Walia, Pediatric Nutrition for Dietitians, 2022
Molly Wong Vega, Poyyapakkam Srivaths
A good understanding of the calcium-parathyroid hormone (PTH)-vitamin D axis is important in the management of phosphorus and calcium in children with CKD. Without activated vitamin D, intestinal absorption of calcium may be poor, signaling increased PTH release causing calcium and phosphorus release from the bone. High phosphorus intake can further increase PTH. Phosphorus and calcium management are important for management of renal osteodystrophy (ROD), growth and prevention of vascular calcifications. Vascular calcifications are a significant risk for cardiovascular morbidity. Dietary phosphorus restriction is extremely difficult in children with CKD due to poor clearance and intake of high phosphorus content foods common in children’s diets. Maintenance of phosphorus levels requires dietary control, ROD medication management, and, when necessary, dialysis. Assessment of phosphorus intake is extremely problematic. Phosphorus is not reported on the nutrition labels. Phosphorus is a hidden additive in food and drink products. Additive sources have a high bioavailability. Appropriate calcium and phosphorus serum levels vary with age and reflect the rate of bone formation; levels are higher at younger ages to support bone accrual. After transplantation, phosphorus levels can be difficult to maintain initially due to high rates of phosphaturia and may even require supplementation. Excessive calcium intake can also be a risk factor for vascular calcification and for this point; it is recommended that the total intake from diet and medications be less than 200% of the DRI for age.
Hepatorenal tyrosinemia/fumarylacetoacetate hydrolase deficiency
Published in William L. Nyhan, Georg F. Hoffmann, Aida I. Al-Aqeel, Bruce A. Barshop, Atlas of Inherited Metabolic Diseases, 2020
William L. Nyhan, Georg F. Hoffmann, Aida I. Al-Aqeel, Bruce A. Barshop
Increased quantities are also excreted in the urine. Of the tyrosyl compounds found in the urine, p-hydroxyphenyllactic acid is the most prominent; p-hydroxyphenylpyruvic acid and p-hydroxyphenylacetic acid are also present in appreciable quantities. Patients often have elevated concentrations of methionine in the blood. Hypoglycemia is common, especially in the acute illness. In chronic cirrhosis or after treatment, tyrosine concentrations may be normal. On the other hand, during the acute stages of hepatocellular damage many other amino acids may be found in elevated amounts in the serum, including cystathionine, proline and hydroxyproline. These patterns, along with the tyrosine, are reflected in the urinary excretion of amino acids. They are superimposed on the generalized aminoaciduria that results from the renal tubular aspects of the disease. Patients also have phosphaturia and hypophosphatemia. The presence of reducing substance completes the picture of the renal Fanconi syndrome. The sugar is usually glucose, but other sugars have been reported [4, 68]. With progression, there is systemic acidosis, increased potassium loss, and hypokalemia.
Chemical, Biochemical, and Medicinal Properties of the Diphosphonates
Published in Richard L. Hilderbrand, The Role of Phosphonates in Living Systems, 2018
Marion D. Francis, Raymond R. Martodam
Doses of HEDP which inhibit bone resorption and mineral deposition and, therefore, the demand for phosphate, markedly reduce the capacity of the tubule of young thyroparathy-roidectomized rats to reabsorb phosphate.186 Inhibition of 1,25(OH)2D3 synthesis by HEDP is not responsible for this phosphaturic effect since HEDP or HEDP and 1,25(OH)2D3 in combination resulted in similar clearance rates for phosphate. Thyroparathyroidectomized rats on a low phosphate diet have a blunted phosphaturic response to PTH which is returned to normal by HEDP. On a high phosphate diet, the phosphaturic response to PTH is enhanced by HEDP. Doses of Cl2MDP which inhibit bone resorption but not mineralization do not affect the renal handling of phosphate. Neither diphosphonate has an effect on the PTH stimulated rise in renal cAMP. This suggests that the decreased tubular reabsorption of phosphate under chronic HEDP treatment but not Cl2MDP represents a homeostatic response of the organism to a decreased skeletal demand for phosphate possibly similar to that observed for calcium (see preceding Section VI.D.1). Alternatively, the phosphaturia may be due to a direct effect on the kidney.
Endocrine fibroblast growth factors as potential biomarkers for chronic kidney disease
Published in Expert Review of Molecular Diagnostics, 2020
Yuichiro Kondo, Hirotaka Komaba, Masafumi Fukagawa
Before reaching end-stage kidney disease (ESKD), normophosphatemia is maintained by the action of FGF23 and PTH to augment phosphaturia, but progression of CKD together with decreased expression of renal α-Klotho [46] leads to a reduction in the ability of the kidney to excrete urinary phosphate, which finally overcomes the compensatory effects of these phosphaturic hormones. This process results in an increase in serum phosphate levels and progressive reduction in 1,25(OH)2D levels, both of which further stimulate PTH secretion [47]. Patients with ESKD thus commonly manifest hyperphosphatemia, decreased levels of 1,25(OH)2D, and secondary hyperparathyroidism. By the time patients start dialysis, FGF23 levels increase markedly and often reach 100–1,000-fold above the normal range [48–54]. Such extremely high FGF23 levels can be primarily attributed to overt hyperphosphatemia, but a variety of other factors may also be involved as mentioned above.
An expert update on novel therapeutic targets for hyperphosphatemia in chronic kidney disease: preclinical and clinical innovations
Published in Expert Opinion on Therapeutic Targets, 2020
Mario Cozzolino, Markus Ketteler, Carsten Alexander Wagner
Renal phosphate reabsorption is mediated to a large extent by the NaPi2a (SLC34A1) phosphate transporter located in the proximal tubule. In analogy to the inhibition of renal glucose reabsorption by SGLT2 inhibitors, inhibition of renal phosphate transporters may lower phosphate burden in patients with earlier stages of CKD (i.e. those with sufficient GFR to filter relevant amounts of phosphate). Inhibitors of NaPi2a have been developed by several companies and are in preclinical testing [92,93]. The PF-06869206 inhibitor induced transient phosphaturia in normal mice and mice with 5/6 nephrectomy lowering plasma phosphate levels [94]. The inhibitor is also effective in increasing renal phosphate excretion in mice lacking FGF-23 or in the adenine-induced CKD mouse model [95]. Similarly, the BAY767 inhibitor also induced phosphaturia and reduced vascular calcifications in a rat model with blocked FGF-23 signaling [93]. Thus, inhibition of renal phosphate reabsorption may be a viable option to lower phosphate in those patients with partly preserved GFR.
Hypotonia and delayed motor development as an early presentation of Lowe syndrome: case report and literature review
Published in Acta Clinica Belgica, 2019
Sara David, Kathleen De Waele, Bram De Wilde, Franny Faes, Olivier Vanakker, Sophie Walraedt, Agnieszka Prytuła
In our patient the presence of tubular proteinuria in urine analysis provided an important clue to diagnosis. Affected boys have varying degrees of renal tubular dysfunction. In early life most children do not exhibit specific symptoms of renal dysfunction. During the first months of life children develop failure to thrive caused by renal bicarbonate, salt and water wasting. Urine analysis at birth shows low-molecular weight proteinuria in all LS patients [7]. This is an interesting finding which can be useful for early diagnosis in patients as this case, when the typical clinical presentation of congenital cataract is absent. Equally, early urine testing is useful in children with congenital cataract, because in the majority of cases of LS, this is the first clinical symptom. When tubular dysfunction becomes more profound later in life, urine analysis can show phosphaturia, aminoaciduria, hypercalciuria, potassium wasting and glycosuria [2].