Glomerular calcification in hypercalcemic nephropathy

Vascular, valvular and kidney calcification manifested in mouse models of adenine-induced chronic kidney disease

BACKGROUND

Ectopic calcification (EC) involves multiple organ systems in chronic kidney disease (CKD). Previous CKD-animal models primarily focused on a certain histological abnormality but did not show the correlation with calcified development among various tissues. This study compared calcified deposition in various tissues during CKD progression in mice.

METHODS

Male 8-week-old C57BL/6J mice were randomly allocated to the seven groups: a basic, adenine, high-phosphorus, or adenine and high-phosphorus diet for 12-16 weeks (Ctl16, A12, P16, or AP16, respectively); an adenine diet for 4-6 weeks; and a high-phosphorus or adenine and high-phosphorus diet for 10-12 weeks (A6 + P10, A4 + P12, or A4 + AP12, respectively).

RESULTS

Compared to the Ctl16 mice, the P16 mice only displayed a slight abnormality in serum calcium and phosphorus; the A12 mice had the most serious kidney impairment; the A4 + P12 and A6 + P10 mice had similar conditions of CKD, mineral abnormalities, and mild calcification in the kidney and aortic valves; the A4 + AP12 and AP16 groups had severe kidney impairment, mineral abnormalities and calcification in the kidneys, aortic valves and aortas. Furthermore, calcium-phosphate particles were deposited not only in the tubulointerstitial compartment but in the glomerular and tubular basement membrane. The elemental composition of EC in various tissues matched the calcification of human cardiovascular tissue as determined by energy dispersive spectroscopy.

CONCLUSIONS

The severity of CKD was unparalleled with the progression of mineral metabolism disorder and EC. Calcification was closely related in different tissues and observed in the glomerular and tubular basement membranes.

Comparison of Pre- and Post-transplant Parathyroidectomy in Renal Transplant Recipients and the Impact of Parathyroidectomy Timing on Calcium Metabolism and Renal Allograft Function: A Retrospective Single-Center Analysis

BACKGROUND

The effect of parathyroidectomy (PTx) timing on serum calcium (Ca) levels and renal functions in renal transplant recipients with severe hyperparathyroidism (HPT) remains unclear. We retrospectively aimed to investigate and compare the clinical data of patients who underwent pre- and post-transplant PTx and elucidated the impact of PTx timing on serum Ca levels and renal graft outcomes after renal transplantation (RTx).

METHODS

During January 2000-December 2016, 53 and 55 patients underwent post-transplant PTx (Post-RTx group) and pretransplant PTx (Pre-RTx group), respectively. The serum Ca levels and estimated glomerular filtration rate (eGFR) were assessed in both groups.

RESULTS

At the end of the follow-up, the serum Ca levels were significantly higher and the incidence of hypocalcemia was significantly lower in the Pre-RTx group than in the Post-RTx group [9.5 vs. 8.9 mg/dL, P < 0.001; 14.5% vs. 34.0%, P = 0.024]. The decrease in the eGFR 12-36 months after RTx was more significant in the Post-RTx group than in the Pre-RTx group (-13.8% vs. -0.9%; P = 0.001). A logistic regression involving age, sex, dialysis period, and serum parathormone level revealed that post-transplant PTx is an independent risk factor for persistent hypocalcemia at the end of the follow-up (P = 0.034) and for a >20% decrease in the eGFR 12-36 months after RTx (P = 0.029).

CONCLUSIONS

In renal transplant candidates with severe HPT, pretransplant PTx should be considered to prevent persistent hypocalcemia and deterioration of the renal graft function.

Glomerular and Tubular Basement Membrane Calcinosis: Case Report and Literature Review

Nephrocalcinosis most commonly manifests as renal calculi or deposition within the tubulointerstitial compartment. Conversely, calcium deposition within glomeruli is extremely rare. We present the case of a 50-year-old man with multiple medical problems, including hepatitis C, diabetes, hypertension, proteinuria, and chronic renal failure. Renal biopsy showed impressive calcium deposits along glomerular basement membranes and tubular basement membranes, within intracellular organelles, and in the interstitium in the setting of a normal serum calcium level. Seven months after biopsy, the patient is on hemodialysis therapy. Although serological and medical examination failed to show a treatable cause for this patient's glomerular calcinosis, individual case reports in the literature have described resolution of calcinosis-associated nephrotic syndrome with treatment of the primary cause of hypercalcemia.

Hyperparathyroidism in the Elderly Patient

Primary hyperparathyroidism is a common metabolic bone disease and currently presents a significant management dilemma. Most of the patients have few relevant symptoms and surgical parathyroidectomy offers the prospect of cure with freedom from the risk of long-term complications or the need for a follow-up. However, there is a natural reluctance to subject elderly patients to an operation where the balance of advantage is less clear. Advances in parathyroid imaging resulting in a greater use of targeted or focused parathyroidectomy has opened the way for the inclusion of less fit patients into the potentially operable category. However, there is still debate about whether these newer imaging techniques are sufficiently helpful and cost effective to warrant their use in all patients who may need parathyroid surgery. This has stimulated a debate about the indications for parathyroidectomy in the elderly and whether advances in medical therapy, which offset the end organ effects of excess parathyroid hormone, are of sufficient benefit to counteract this trend towards greater surgical intervention. These considerations mean that it is not possible to consider the merits of pharmacological therapy for primary hyperparathyroidism without reviewing the relative merits of minimally invasive and conventional surgery.