Vasopressin function in hypercalcaemia

Hospital-Acquired Serum Ionized Calcium Derangements and Their Associations with In-Hospital Mortality

Background: The objective of this study was to report the incidence of in-hospital serum ionized calcium derangement and its impact on mortality. Methods: We included 12,599 non-dialytic adult patients hospitalized at a tertiary medical center from January 2009 to December 2013 with normal serum ionized calcium at admission and at least 2 in-hospital serum ionized calcium values. Using serum ionized calcium of 4.60–5.40 mg/dL as the normal reference range, in-hospital serum ionized calcium levels were categorized based on the presence of hypocalcemia and hypercalcemia in hospital. We performed logistic regression to assess the relationship of in-hospital serum ionized calcium derangement with mortality. Results: Fifty-four percent of patients developed new serum ionized calcium derangements: 42% had in-hospital hypocalcemia only, 4% had in-hospital hypercalcemia only, and 8% had both in-hospital hypocalcemia and hypercalcemia. In-hospital hypocalcemia only (OR 1.28; 95% CI 1.01–1.64), in-hospital hypercalcemia only (OR 1.64; 95% CI 1.02–2.68), and both in-hospital hypocalcemia and hypercalcemia (OR 1.73; 95% CI 1.14–2.62) were all significantly associated with increased in-hospital mortality, compared with persistently normal serum ionized calcium levels. Conclusions: In-hospital serum ionized calcium derangements affect more than half of hospitalized patients and are associated with increased in-hospital mortality.

Impact of Changes in Serum Calcium Levels on In-Hospital Mortality

Background and objectives: Calcium concentration is strictly regulated at both the cellular and systemic level, and changes in serum calcium levels can alter various physiological functions in various organs. This study aimed to assess the association between changes in calcium levels during hospitalization and mortality. Materials and Methods: We searched our patient database to identify all adult patients admitted to our hospital from January 1st, 2009 to December 31st, 2013. Patients with ≥2 serum calcium measurements during the hospitalization were included. The serum calcium changes during the hospitalization, defined as the absolute difference between the maximum and the minimum calcium levels, were categorized into five groups: 0–0.4, 0.5–0.9, 1.0–1.4, 1.5–1.9, and ≥2.0 mg/dL. Multivariable logistic regression was performed to assess the independent association between calcium changes and in-hospital mortality, using the change in calcium category of 0–0.4 mg/dL as the reference group. Results: Of 9868 patients included in analysis, 540 (5.4%) died during hospitalization. The in-hospital mortality progressively increased with higher calcium changes, from 3.4% in the group of 0–0.4 mg/dL to 14.5% in the group of ≥2.0 mg/dL (p < 0.001). When adjusted for age, sex, race, principal diagnosis, comorbidity, kidney function, acute kidney injury, number of measurements of serum calcium, and hospital length of stay, the serum calcium changes of 1.0–1.4, 1.5–1.9, and ≥2.0 mg/dL were significantly associated with increased in-hospital mortality with odds ratio (OR) of 1.55 (95% confidence interval (CI) 1.15–2.10), 1.90 (95% CI 1.32–2.74), and 3.23 (95% CI 2.39–4.38), respectively. The association remained statistically significant when further adjusted for either the lowest or highest serum calcium. Conclusion: Larger serum calcium changes in hospitalized patients were progressively associated with increased in-hospital mortality.

Hypercalcemia Heralding Pneumocystis jirovecii Pneumonia in an HIV-Seronegative Patient with Diffuse Cutaneous Systemic Sclerosis

Pneumocystis pneumonia (PCP) is a life-threatening fungal infection occurring in immunocompromised patients such as HIV-positive patients with low CD4 cell count or patients under heavy immunosuppressive therapy. We report the case of a 59-year-old male with severe diffuse cutaneous systemic sclerosis presenting with asthenia, dry cough and worsening shortness of breath for the last 15 days. Biological studies were remarkable for PTH-independent severe hypercalcemia with low 25-hydroxyvitamin D and a paradoxically elevated 1,25-dihydroxyvitamin D. Early bronchoalveolar lavage allowed for PCP diagnosis and targeted treatment. We discuss the underlying physiopathology and difficulties regarding prophylaxis and treatment.

Elevated admission serum calcium phosphate product as an independent risk factor for acute kidney injury in hospitalized patients

BACKGROUND

Increased serum calcium-phosphate product (CaP) can result in acute kidney injury (AKI) due to tubular and interstitial calcium phosphate deposits. CaP of > 55 mg²/dL² is also associated with systemic calcification. However, the risk of AKI development among hospitalized patients with different admission calcium-phosphate product levels remains unclear.

METHODS

All adult hospitalized patients who had both admission serum calcium and phosphate levels available from 2009 through 2013 were enrolled. Admission CaP was categorized based on its distribution into six groups (<22, 22- < 27, 27- < 32, 32- < 37, 37- < 42 and ≥42 mg²/dL²). The odds ratio (OR) of in-hospital mortality by admission CaP, using the CaP category of < 22 mg²/dL² as the reference group, was obtained by logistic regression analysis.

RESULTS

After excluding patients with end-stage renal disease, without serum creatinine measurement, and those who presented with AKI at the time of admission, a total of 9,864 patients were studied. In-hospital AKI occurred in 1,478 patients (15.0%). The incidence of AKI among patients with admission CaP < 22, 22 to < 27, 27 to < 32, 32 to < 37, 37 to < 42, and ≥42 mg²/dL² was 11.1%, 12.4%, 14.9%, 15.2%, 17.5%, and 19.9%, respectively. After adjusting for potential confounders, a CaP ≥37 mg²/dL² was associated with an increased risk of developing AKI with OR of 1.53 (CI 1.19-1.96) and 1.63 (CI 1.25-2.14) in patients with admission CaP 37- < 42 and ≥42, respectively. Subgroup analysis based on eGFR consistently demonstrated that CaP ≥37 mg²/dL² was associated with an increased risk of developing AKI in both chronic kidney disease (CKD) and non-CKD patients.

CONCLUSION

Elevated admission CaP was independently associated with an increased risk for in-hospital AKI.

Admission calcium levels and risk of acute kidney injury in hospitalised patients

BACKGROUND

The risk of acute kidney injury (AKI) development among hospitalised patients with elevated calcium levels on admission remains unclear. The aim of this study was to assess the risk of AKI in hospitalised patients stratified by various admission serum calcium levels.

METHODS

This is a single-centre retrospective study conducted at a tertiary referral hospital. All hospitalised adult patients who had admission calcium levels available between 2009 and 2013 were enrolled. Admission calcium was categorised based on its distribution into six groups (≤7.9, 8.0-8.4, 8.5-8.9, 9.0-9.4, 9.5-9.9, and ≥10.0 mg/dL). The primary outcome was hospital-acquired AKI. Logistic regression analysis was performed to obtain the odds ratio of AKI for various admission calcium strata using calcium levels of 8.0-8.4 mg/dL (lowest incidence of AKI) as the reference group.

RESULTS

A total of 12 784 patients were studied. Hospital-acquired AKI occurred in 1779 (13.9%) patients. The incidence of AKI among patients with admission calcium ≤7.9, 8.0-8.4, 8.5-8.9, 9.0-9.4, 9.5-9.9 and ≥10 mg/dL was 14.7%, 11.7%, 11.8%, 14.6%, 15.8% and 17.3%, respectively. After adjusting for potential confounders, admission calcium levels ≤7.9, 9.0-9.4, 9.5-9.9 and ≥10 mg/dL were associated with increased risk of AKI with odds ratios of 1.36 (95%CI 1.08-1.72), 1.29 (95%CI 1.08-1.56), 1.38 (95%CI 1.14-1.68) and 1.51 (95%CI 1.19-1.91), respectively.

CONCLUSION

Admission hypocalcaemia and hypercalcaemia are associated with an increased risk for hospital acquired AKI. Patients with admission hypercalcaemia (≥10 mg/dL) carry a 1.51-fold risk for AKI development during hospitalisation.

Arginine-vasopressin directly promotes a thermogenic and pro-inflammatory adipokine expression profile in brown adipocytes

Arginine-vasopressin (AVP) - via activation of the hypothalamic-pituitary-adrenal (HPA) axis - may play a role in the regulation of energy homeostasis and related cardiovascular complications. Brown adipose tissue (BAT) - via dissipation of energy in the form of heat - contributes to whole body energy balance. BAT expresses vasopressin receptors. We investigated direct effects of AVP on brown adipose endocrine and metabolic functions. UCP-1 protein expression in differentiated brown adipocytes was induced after acute exposure of adipocytes to AVP. This effect was time-dependent with a maximum increase after 8h. AVP also induced a time- and dose-dependent increase in p38 MAP kinase phosphorylation. Pharmacological inhibition of p38 MAP kinase with SB 202190 abolished the induction of UCP-1 protein expression. Furthermore, while acute AVP treatment enhanced mRNA expression of MCP-1 and IL-6, adiponectin mRNA expression was reduced. Yet, on the level of intracellular glucose uptake, there was no AVP-induced change of adipose insulin-induced glucose uptake. Finally, there was no difference in lipid accumulation between control and AVP-treated cells. Taken together, our data demonstrate direct effects of AVP on thermogenic, inflammatory, and glucoregulatory gene expression in brown adipocytes, thus expanding the hitherto known spectrum of this neuropeptides's biological effects and suggesting a direct adipotropic role as a stress-promoting factor.

Causes of reversible nephrogenic diabetes insipidus: A systematic review

BACKGROUND

In nephrogenic diabetes insipidus (NDI), the kidney is unable to produce concentrated urine because of the insensitivity of the distal nephron to antidiuretic hormone (arginine vasopressin). In settings in which fluid intake cannot be maintained, this may result in severe dehydration and electrolyte imbalances. The risk for conversion of reversible to irreversible NDI seems to be a potential complication. This review summarizes the reversible causes of acquired NDI to facilitate earlier recognition and more effective treatment by clinicians.

METHODS

Two reviewers independently searched MEDLINE, Experta Medica (EMBASE), and ISI bibliographic databases. Human studies that described NDI caused by drugs, substances, or metabolic disturbances were included. To evaluate the causal role of the risk factor, data were abstracted according to Koch's postulates.

RESULTS

One hundred fifty-five studies published between 1957 and March 2004 described 30 risk factors. Of 155 studies, 58 studies provided a "definite" diagnosis of NDI; 83 studies, a "probable" diagnosis; and 14 studies, a "possible" diagnosis. Nine factors were considered "definite" causes of NDI; 15 factors, "probable" causes; and 6 factors, "possible" causes. The most reported risk factors were lithium (84 studies), antibiotics (16 studies), antifungals (11 studies), antineoplastic agents (9 studies), antivirals (8 studies), and metabolic disturbances (8 studies). Duration of NDI reversal, as well as conversion to irreversible symptoms, seemed to depend on the duration of exposure.

CONCLUSION

Most risk factors for reversible NDI were medications, and their identification and removal resulted in resolution of the condition. Long-term treatment with lithium seemed to result in irreversible NDI.

Parathyroid hormone immunohistochemistry in dogs with primary and secondary hyperparathyroidism: the question of adenoma and primary hyperplasia

In primary hyperparathyroidism, calcium homeostasis is disrupted by excessive synthesis and secretion of parathyroid hormone (PTH), which is usually caused by a solitary adenoma, or less often by nodular hyperplasia or carcinoma of the parathyroid glands. So far, the distinction between these forms of primary hyperparathyroidism has been made by histological examination. In this report clinical and histological findings, including PTH immunohistochemistry, are described in five dogs with primary hyperparathyroidism, three dogs with secondary hyperparathyroidism due to chronic renal failure, and eight control dogs. In the dogs with primary hyperparathyroidism, nodular adenomatous hyperplasia was found in two animals and parathyroid adenoma in three. The dogs with chronic renal failure had diffuse parathyroid gland hyperplasia. The parathyroid glands of the control dogs and the inactive cells surrounding the hyperplastic nodules showed slight to moderate, localized, paranuclear PTH immunolabelling. In the primary nodular and secondary diffuse hyperplasia, all parathyroid cells had a diffuse cytoplasmic PTH labelling pattern, sometimes in combination with localized paranuclear labelling. In parathyroid adenoma, areas with either paranuclear labelling or diffuse cytoplasmic labelling were observed. As both parathyroid adenoma and primary nodular parathyroid gland hyperplasia have characteristics of intrinsic autonomy (i.e., suppression of the remaining endocrine tissue), there would seem to be no functional difference between the two abnormalities. It is argued that primary (multi)nodular hyperplasia is a multiple form of parathyroid adenoma.

Systemic diseases associated with disorders of water homeostasis

Disorders of AVP secretion and action sometimes present as the first manifestation of a variety of different systemic diseases. It is prudent for the clinician to consider these causes in the differential diagnosis of hypoosmolar hyponatremia, polyuria and polydipsia, since recognizing the underlying disorder may affect treatment decisions, and intervention directed at the primary disorder often can reverse the abnormal water metabolism in these patients. Although much of the pathophysiology of these disorders is not understood completely, great progress has been made toward appreciating the complex and precise system involving thirst, AVP secretion, and renal responsiveness to AVP. Further investigation in this field likely will allow physicians to offer more effective and potent treatments in the future, such as the development of AVP V2 receptor antagonists for the treatment of SIADH [81] and edema-forming states [18, 109].

Nephrogenic diabetes insipidus persisting 57 months after cessation of lithium carbonate therapy: report of a case and review of the literature

OBJECTIVE

To illuminate the natural history of prolonged nephrogenic diabetes insipidus after discontinuation of lithium carbonate treatment and to assess the response to therapy with desmopressin acetate and triamterene-hydrochlorothiazide.

METHODS

We analyzed sequential determinations of serum and urine osmolality, plasma arginine vasopressin, serum sodium, blood urea nitrogen, calcium, ionized calcium, parathyroid hormone, and 24-hour urine volume during a period of 57 months in a 67-year-old woman.

RESULTS

Our patient experienced persistent polyuria in conjunction with having repeated serum osmolalities between 300 and 323 mOsm/kg and urine osmolalities between 130 and 208 mOsm/kg. Concomitant plasma arginine vasopressin levels were as high as 12.0 pg/mL, consistent with the diagnosis of nephrogenic diabetes insipidus. Administration of triamterene-hydrochlorothiazide reduced 24-hour urine volume and serum osmolality while increasing urine osmolality. Desmopressin acetate exhibited no effect.

CONCLUSION

In this report, we describe the eighth documented case of persistent nephrogenic diabetes insipidus, lasting 57 months after cessation of lithium therapy, and demonstrate a palliative effect of triamterene-hydrochlorothiazide.

Arginine vasopressin and osmolality in the elderly

OBJECTIVES

To evaluate the influence of age on plasma arginine vasopressin (AVP) concentrations and the relationship between plasma AVP and serum osmolality in younger and older subjects, and in the elderly, to assess the effect of gender on plasma AVP concentration and to determine the impact of prostaglandin blockade on renal responsiveness to AVP.

DESIGN

Cross-sectional study; randomized, double-blind, crossover, placebo-controlled study.

SETTING

The Renal Laboratory, Royal North Shore Hospital (younger adults) and Clinical Room, St Vincents Hospital (elderly subjects).

PARTICIPANTS

45 younger adults (35 +/- 9 years), and 41 elderly subjects (29 males, 12 females; 78 +/- 3 years). All subjects were healthy and non-institutionalized. The elderly subjects were screened to exclude significant pathology (clinical assessment, multiple investigations).

INTERVENTION

Blood samples were drawn from all younger and elderly subjects. The elderly subjects were randomly allocated indomethacin or placebo for 1 month. Following a 1 to 2-week washout, the alternative was administered for a further 1 month.

MAIN OUTCOME MEASURES

Plasma AVP and serum osmolality and plasma AVP, serum, and urine osmolality at baseline were measured on indomethacin and placebo.

RESULTS

In the elderly subjects, baseline plasma AVP concentration was significantly higher than in the younger subjects studied (4.7 +/- 0.7 vs 2.1 +/- 0.2 pg/mL respectively; P = 0.0003). Plasma AVP was strongly correlated with serum osmolality in the younger subjects (r = 0.76, P = 0.0001) but not in the elderly cohort (r = -0.18, P = 0.26). No difference was found between the sexes in plasma AVP (P = 0.89), and indomethacin treatment did not alter the plasma AVP/urine osmolality ratio (P = 0.85) in the elderly subjects. In addition, changes in plasma AVP with indomethacin therapy did not correlate with changes in serum osmolality (r = 0.16, P = 0.09).

CONCLUSIONS

Aging is accompanied by an increase in plasma AVP concentrations. In healthy, elderly subjects, plasma AVP is not dependent on serum osmolality and is not influenced by gender. Indomethacin has no effect on the renal responsiveness to plasma AVP.

Pre- and postoperative evaluation of renal function with five different tests in patients with primary hyperparathyroidism

Renal function was investigated immediately before and 1 year following parathyroidectomy in 19 patients with moderate hypercalcaemia. On both occasions, all patients underwent five different tests of glomerular and tubular function: plasma creatinine, creatinine clearance, 51Cr-EDTA-clearance, beta 2-microglobulin excretion and the desmopressin test. Glomerular filtration rate, as assessed by plasma creatinine and clearance of both creatinine and 51Cr-EDTA, was normal in most patients, and was little affected by restoration of normocalcaemia. Renal concentrating capacity, as determined by the desmopressin test, was abnormally low in 14 of 19 patients, but increased significantly after surgery. It is concluded that serious renal damage is seldom encountered in present-day HPT patients, but that a treatable decrease in renal concentrating capacity often exists.

Polyuric states in man

This chapter reviews the pathophysiological basis for the mechanisms of polyuria and discusses the causes in detail. A small proportion of patients with CDI are of the idiopathic type, with the majority of causes due to trans-spenoidal surgery, head injury following road traffic accidents, and an autoimmune variant. Indirect methods of investigating polyuria are inaccurate in a significant proportion of cases, and the incorporation of measurements of plasma AVP into a water-deprivation test or hypertonic saline infusion can improve diagnostic accuracy. Non-osmotic tests of AVP secretion are of no value in the differential diagnosis of polyuria. Most patients with CDI can maintain water homeostasis with adequate fluid intake, but desmopressin is a convenient, effective and safe therapy which is recommended on both social and medical grounds. Treatment of NDI remains problematic, as neither thiazide diuretics or indomethacin can completely abolish polyuria, and fluid intake remains of primary importance.

Effects of calcium on vasopressin-mediated cyclic adenosine monophosphate formation in cultured rat inner medullary collecting tubule cells. Evidence for the role of intracellular calcium

We explored the effects of alterations in extracellular and intracellular calcium concentration on arginine vasopressin (AVP)-stimulated cAMP formation in cultured rat inner medullary collecting tubule cells. cAMP formation remains constant at extracellular calcium concentrations between 0.5 and 4.0 mM, which did not change intracellular calcium. Maneuvers that alter intracellular calcium concentration are associated with marked changes in cAMP generation. EGTA decreases intracellular calcium and enhances AVP-stimulated cAMP formation, while increasing cellular calcium with 2 microM A23187 decreases AVP-stimulated cAMP formation in the presence, but not in the absence, of extracellular calcium. The changes in cAMP formation observed when intracellular calcium is altered are associated with reciprocal changes in prostaglandin E2 (PGE2) synthesis. Despite greater than 95% inhibition of PGE2 synthesis with 5 microM meclofenamic acid, the changes in cAMP formation accompanying alterations in intracellular calcium concentration are still evident. These studies suggest that intracellular calcium critically influences AVP-stimulated cAMP formation. It does so by a mechanism independent of PG that is probably mediated by a direct effect of the cation on the adenylate cyclase complex.

Differential laboratory diagnosis of hypercalcemia

It is proposed that this review will adopt the following format: establishment of hypercalcemia. This demands a discussion of the problem of normal ranges, the usage of either total calcium or ionized calcium in making this decision and where total calcium is used whether adjustment of this value for serum protein concentration should be used and if so, the formulae which have been cited to perform this. Having established hypercalcemia why is it necessary to differentiate this? This will involve reviewing those clinical situations in which differentiation of hypercalcemia has been attempted and will include an attempt to produce an up to date indication of conditions in which hypercalcemia has been described. When hypercalcemia has been established the laboratory tests which have been further used to discriminate will be divided into single tests such as N- or C- terminal parathormone, 1,25- dihydroxycholecalciferol, cyclic AMP; the combination tests which have been used including phosphate clearance, chloride vs. bicarbonate etc. proceeding to those groups which have used discriminant function to help in the decision making; dynamic testing will also be discussed particularly with reference to steroid suppression but will also include other known suppressants such as Mithramycin and Calcitonin. A final section will be included attempting to assess overall the present state of art in differentiating laboratory diagnosis of hypercalcemia and will also attempt to highlight those areas which appear to be most fruitful areas of progress in the future.

Posterior pituitary function in health and disease

This chapter has reviewed briefly the neuroanatomy relevant to the synthesis and release of AVP and OXT. Osmoregulation and baroregulation of AVP secretion has been discussed in detail, emphasizing the importance of osmotic control under normal physiological conditions. The remainder of the text has covered the two major pathophysiological disturbances of AVP secretion. In considering diabetes insipidus a pragmatic approach has been taken in the differentiation of the causes of polyuria and its treatment. A similar approach has been applied to the syndrome of inappropriate antidiuresis. Brief mention was made of the function of OXT.

Plasma vasopressin in hypercalcaemic states

Plasma vasopressin was measured by radioimmunoassay in eight normal subjects and in six patients with hypercalcaemia. Vasopressin levels were significantly elevated in the hypercalcaemic patients, although urine osmolalities were lower than in controls. This finding is consistent with a renal resistance to the action of endogenous vasopressin in hypercalcaemia.