Accuracy of methods to estimate ionized and "corrected" serum calcium concentrations in critically ill multiple trauma patients receiving specialized nutrition support

Evaluation of a Novel Enteral Phosphorus Therapy with Enteral Nutrition during a National Intravenous Sodium Phosphate Shortage

The purpose of this study was to evaluate the efficacy and safety of intragastric administration of small volumes of sodium enema solution containing phosphorus as phosphorus replacement therapy in critically ill patients with traumatic injuries who required continuous enteral nutrition. Adult patients (>17 years of age) who had a serum phosphorus concentration <3 mg/dL (0.97 mmol/L) were evaluated. Patients with a serum creatinine concentration >1.4 mg/dL (124 µmol/L) were excluded. Patients were given 20 mL of saline enema solution intragastrically, containing 34 mmol of phosphorus and mixed in 240 mL water. A total of 55% and 73% of patients who received one (n = 22) or two doses (n = 11) had an improvement in the serum phosphorus concentration, respectively. The serum phosphorus concentration increased from 2.5 [2.1, 2.8] mg/dL (0.81 [0.69, 0.90] mmol/L) to 2.9 [2.2, 3.0] mg/dL (0.94 [0.71, 0.97 mmol/L) for those who received two doses (p = 0.222). Excluding two patients with a marked decline in serum phosphorus by 1.3 mg/dL (0.32 mmol/L) resulted in an increase in the serum phosphorus concentration from 2.3 [2.0, 2.8] mg/dL (0.74 [0.65, 0.90] mmol/L) to 2.9 [2.5, 3.2] mg/dL (0.94 [0.81, 1.03] mmol/L; n = 9; p = 0.012). No significant adverse effects were noted. Our data indicated that intragastric phosphate administration using a small volume of saline enema solution improved the serum phosphorus concentrations in most patients.

Primary hyperparathyroidism in adults-(Part I) assessment and medical management: Position statement of the endocrine society of Australia, the Australian & New Zealand endocrine surgeons, and the Australian & New Zealand bone and mineral society

OBJECTIVE

To formulate clinical consensus recommendations on the presentation, assessment, and management of primary hyperparathyroidism (PHPT) in adults.

METHODS

Representatives from relevant Australian and New Zealand Societies used a systematic approach for adaptation of guidelines (ADAPTE) to derive an evidence-informed position statement addressing nine key questions.

RESULTS

PHPT is a biochemical diagnosis. Serum calcium should be measured in patients with suggestive symptoms, reduced bone mineral density or minimal trauma fractures, and in those with renal stones. Other indications are detailed in the manuscript. In patients with hypercalcaemia, intact parathyroid hormone, 25-hydroxy vitamin D, phosphate, and renal function should be measured. In established PHPT, assessment of bone mineral density, vertebral fractures, urinary tract calculi/nephrocalcinosis and quantification of urinary calcium excretion is warranted. Parathyroidectomy is the only definitive treatment and is warranted for all symptomatic patients and should be considered for asymptomatic patients without contraindications to surgery and with >10 years life expectancy. In patients who do not undergo surgery, we recommend annual evaluation for disease progression. Where the diagnosis is not clear or the risk-benefit ratio is not obvious, multidisciplinary discussion and formulation of a consensus management plan is appropriate. Genetic testing for familial hyperparathyroidism is recommended in selected patients.

CONCLUSIONS

These clinical consensus recommendations were developed to provide clinicians with contemporary guidance on the assessment and management of PHPT in adults. It is anticipated that improved health outcomes for individuals and the population will be achieved at a decreased cost to the community.

Serum 25(OH)D levels are associated with disease activity and renal involvement in initial-onset childhood systemic lupus erythematosus

Background

Vitamin D deficiency is common in patients with systemic lupus erythematosus (SLE) and may affect their disease activity and severity.

Objective

This study aims to assess the vitamin D status in patients with initial-onset SLE during childhood and its association with the clinical and laboratory markers of disease activity.

Method

This is a retrospective study that includes 168 patients with initial-onset SLE during childhood and 109 healthy children as controls. Clinical and laboratory data were recorded. The area under the curve (AUC) method was used to evaluate the efficacy of double-stranded deoxyribonucleic acid (dsDNA), lower 25(OH)D and complement 3 (C3) alone and in combination to diagnose the presence of renal damage in children with SLE.

Result

Compared with the controls (25.53 ± 7.02 ng/ml), patients with initial-onset SLE during childhood have lower serum 25(OH)D levels (18.63 ± 5.32 ng/ml) (P < 0.05). Among patients with initial-onset SLE during childhood, SLEDAI-2K scores are significantly higher in the vitamin D insufficiency (median = 14.5) and vitamin D deficiency (median = 14.0) groups than in the vitamin D sufficiency group (median = 9.0) (P < 0.05). Patients with initial-onset SLE during childhood with lower 25(OH)D levels are more likely to have lupus nephritis (LN) and a higher SDI score (P < 0.05). Compared with patients with other types of LN (16.69 ± 3.90 ng/ml), patients with type V LN have lower levels of 25(OH)D (12.27 ± 3.53 ng/ml) (P < 0.05). The AUC was 0.803 when dsDNA antibody, 25(OH)D level and C3 were used in combination to diagnose LN in patients with SLE.

Conclusion

Vitamin D deficiency and insufficiency are closely related to an increase in SLEDAI and SDI scores. Significant decrease in vitamin D level is a risk factor for LN.

A new approach to assessing calcium status via a machine learning algorithm

BACKGROUND AND AIMS

Calcium plays a fundamental role in biological processes. Ionized calcium (Ca²⁺), is the biologically active fraction, but in practice total or corrected calcium assays are routinely used to determine calcium status.

MATERIALS AND METHODS

We retrospectively compared total and corrected calcium to assess the calcium status, with ionized calcium which is considered for now like the best indicator. To compensate for their lack of performance we created a machine learning algorithm to predict calcium status.

RESULTS

Corrected calcium performed less well than total calcium with 58% and 74% agreement, respectively, in our population. Total calcium was especially good for hypocalcemic samples: 93% agreement versus 45% for normocalcemic and 54% for hypercalcemic samples. Corrected calcium was especially good for hypercalcemic and normocalcemic samples: 90% and 84% agreement respectively versus 40% for hypocalcemic samples. Corrected calcium is mainly faulty in hypoalbuminemia, acid-base disorders, renal insufficiency, hyperphosphatemia, or inflammatory syndrome. With our ML algorithm, we obtained 81% correct classifications. Its main advantage is that its performance are not influenced by the variables studied or the calcium status.

CONCLUSION

In many situations, corrected calcium should not be used. Our ML algorithm may make a better assessment of calcium status than total calcium. Finally, if doubt, an ionized calcium assay should be performed.

The Potential Role of Model for End-Stage Liver Disease (MELD)-Sodium Score in Predicting the Severity of Acute Pancreatitis

Background and aim Acute pancreatitis is a common inflammation of the pancreas which can be severe and even potentially mortal. High rates of mortality showed the importance of immediate identification of patients at high risk and led the clinicians to refer to various scoring systems. Our aim was to investigate a clinical predictive model using the Model for End-Stage Liver Disease-Sodium (MELD-sodium) scoring system, adapting it to acute pancreatitis patients referring to the systemic inflammatory nature of the disease and potential multi-organ failures in severe form. Methods Our multicenter study was designed retrospectively. The medical records were reviewed for the period of two years. Demographics, biochemical results, MELD-sodium scores and mortality rates were analysed. Results MELD-sodium score was found to be statistically correlated with both mortality and the severity of pancreatitis (p<0.001) and significant difference between both mild and severe (p<0.001), moderate and severe groups (p<0.001). Mortality was found to be significantly higher in patients with MELD-Na score when the cut-off value was accepted as '≥11'. Conclusion We found that MELD-sodium score was significantly associated with both severity of disease and mortality rates and also significantly effective between both mild/severe and moderate/severe groups which may be a guide for future multi-center reviews with larger patient and control groups, which can define the potential role of this non-invasive and easy-to-use predictive model in acute pancreatitis patients.

Plasma Levels of Intact Parathyroid Hormone and Congestion Burden in Heart Failure: Clinical Correlations and Prognostic Role

Circulating parathyroid hormone (PTH) concentrations increase in heart failure (HF) and are related to disease severity. The relationship between PTH and congestion is still a matter of debate. The objective of this analysis was to evaluate the role of PTH as a marker of congestion and prognosis in HF. We enrolled 228 patients with HF. Intact PTH concentrations and HYDRA score (constituted by: B-type natriuretic peptide, blood urea nitrogen−creatinine ratio, estimated plasma volume status, and hydration status) were evaluated. The study endpoint was all-cause mortality. PTH levels were higher in acute compared with chronic HF and in patients with clinical signs of congestion (i.e., peripheral oedema and orthopnea). PTH concentrations significantly correlated with NYHA class and HYDRA score. At multivariate analysis of HYDRA score, estimated glomerular filtration rate (eGFR), and corrected serum calcium were independently determinants of PTH variability. Fifty patients (22%) died after a median follow-up of 408 days (interquartile range: 283−573). Using univariate Cox regression analysis, PTH concentrations were associated with mortality (hazard ratio [HR]: 1.003, optimal cut-off: >249 pg/mL—area under-the-curve = 0.64). Using multivariate Cox regression analysis, PTH was no longer associated with death, whereas HYDRA score, left ventricular ejection fraction, and eGFR acted as independent predictors for mortality (HR: 1.96, 0.97, and 0.98, respectively). Our study demonstrated that intact PTH was related to clinical and subclinical markers of congestion. However, intact PTH did not act as an independent determinant of all-cause death in HF patients.

Trauma-related electrolyte disturbances: From resuscitation to rhabdomyolysis

Traumatic injury results in drastic changes to a patient's normal physiology. The hormonal stress response, as well as some treatment strategies, lead to significant disruptions in electrolyte homeostasis that are important for clinicians to understand. In addition, advances in fluid resuscitation and modern transfusion practices have led to their own unique set of consequences, which we are just beginning to appreciate. Special attention is placed on rhabdomyolysis, as this distinct entity represents an extreme example of injury induced electrolyte derangements. This review describes the physiologic response to trauma and highlights some of the important electrolyte abnormalities that can be encountered while caring for the injured patient.

Corrected Serum Ionized Calcium as a Risk Factor Related to Adult Dyslipidemia

Background

Dyslipidemia is a significant threat to global public health due to its pivotal role as a cardiovascular disease (CVD) risk factor. Calcium is a critical nutritional element required for electrical signal transduction and muscle and heart function, and calcium supplementation is widespread in the general population. However, associations between serum calcium and serum lipid profiles remain conflicting. Considering ionized calcium [Ca(2+)] is the best measure of active serum calcium and the lack of Ca(2+) analyzers, we aimed to examine the independent and joint associations between serum ionized calcium corrected by albumin ([Ca2+]corr) and the known modifiable risk factors and dyslipidemia.

Methods

We collected physical examination records, including demographic, anthropometric, laboratory tests, and clinical characteristics from individuals who had health checkups in 2019 at the health examination center of the First Affiliated Hospital of China Medical University. Subjects were categorized into Q1–Q4 groups using [Ca2+]corr quartiles, and odds ratios (ORs) with 95% confidence intervals (CIs) for dyslipidemia and associated components were calculated using logistic regression. We also performed non-linear and threshold effect analyses of [Ca2+]corr and triglyceride (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), and non-high-density lipoprotein cholesterol (Non-HDL-C) levels.

Findings

Of 5,416 individuals aged 18–92 years, multivariable-adjusted models showed that ORs for dyslipidemia increased gradually with elevated [Ca2+]corr levels. Logistic regression analyses demonstrated that [Ca2+]corr levels were associated with the increased odds of dyslipidemia (per 1 mmol/L increase: OR = 3.53, 95% CI: 1.56–8.00, P < 0.001). When compared with individuals in the Q1 group, those in groups Q3 and Q4 had significantly higher dyslipidemia odds (OR_{Q3 vs. Q1} = 1.20, 95% CI: 1.01–1.42; OR_{Q4 vs. Q1} = 1.31, 95% CI: 1.10–1.56, all P < 0.05). Furthermore, a linear, positive relationship between [Ca2+]corr levels and dyslipidemia odds was observed (P for non-linear trend = 0.506), and the optimal cut-off point of [Ca2+]corr for dyslipidemia management was 2.26 mmol/L. A modifiable effect of albumin on the relationship between [Ca2+]corr and dyslipidemia odds was also found (P for interaction = 0.014). High [Ca2+]corr levels were positively associated with elevated TC, LDL-C, and Non-HDL-C but inversely associated with decreased HDL-C odds. Moreover, Locally weighted regression (Loess) analyses showed a non-linear, positive relationship between [Ca2+]corr and TG, TC, HDL-C, LDL-C, and Non-HDL-C levels.

Interpretation

Corrected serum ionized calcium was positively associated with increased odds of dyslipidemia and elevated TC, LDL-C, and Non-HDL-C, but inversely associated with the odds of decreased HDL-C.

Hypocalcemia in hospitalized patients with COVID-19: roles of hypovitaminosis D and functional hypoparathyroidism

INTRODUCTION

Despite the high prevalence of hypocalcemia in patients with COVID-19, very limited studies have been designed to evaluate etiologies of this disorder. This study was designed to evaluate the status of serum parameters involved in calcium metabolism in patients with COVID-19 and hypocalcemia.

MATERIALS AND METHODS

This cross-sectional study was conducted on 123 hospitalized patients with COVID-19. Serum concentrations of PTH, 25 (OH) D, magnesium, phosphate, and albumin were assessed and compared across three groups of moderate/severe hypocalcemia (serum total calcium < 8 mg/dl), mild hypocalcemia (8 mg/dl ≤ serum total calcium < 8.5 mg/dl) and normocalcemia (serum total calcium ≥ 8.5 mg/dl). Multivariate analyses were performed to evaluate the independent roles of serum parameters in hypocalcemia.

RESULTS

In total, 65.9% of the patients had hypocalcemia. Vitamin D deficiency was found in 44.4% and 37.7% of moderate/severe and mild hypocalcemia cases, respectively, compared to 7.1% in the normal serum total calcium group (P = 0.003). In multivariate analysis, vitamin D deficiency was independently associated with 6.2 times higher risk of hypocalcemia (P = 0.001). Only a minority of patients with hypocalcemia had appropriately high PTH (15.1% and 14.3% in mild and moderate/severe hypocalcemia, respectively). Serum PTH was low/low-normal in 40.0% of patients with moderate/severe low-corrected calcium group. Magnesium deficiency was not associated with hypocalcemia in univariate and multivariate analysis.

CONCLUSION

Vitamin D deficiency plays a major role in hypocalcemia among hospitalized patients with COVID-19. Inappropriately low/low-normal serum PTH may be a contributing factor in this disorder.

A Comparison of the Commonly Used Surrogate Markers for Citrate Accumulation and Toxicity during Continuous Renal Replacement Therapy with Regional Citrate Anticoagulation

INTRODUCTION

Continuous renal replacement therapy using regional citrate anticoagulation is commonly used as a modality of organ support in the critically ill population. Currently, citrate accumulation or toxicity is assessed using surrogate markers, notably the uncorrected total-to-ionized calcium ration. The accuracy and utility of this method have been questioned.

OBJECTIVES/AIMS

The aim of this study was to compare the surrogate markers used for assessing citrate accumulation or toxicity using the measurement of plasma citrate as the gold standard.

METHODS

Blood was sampled from 20 patients before, during, and after episodes of filtration with citrate concentration measured using spectrophotometry. Demographic and other clinical and biochemical data were also collected. According to protocol, a 15 mmol/L solution of trisodium citrate was used as the prefilter anticoagulant. Results were analyzed using STATA (v16.0) and presented as mean (SD), median (IQR), or simple proportion. Univariate linear regression using citrate concentration as the dependent variable was performed with all surrogate markers.

RESULTS

Twenty patients (17 males) were enrolled in the study with a mean (SD) age of 62.7 (9.9) years. The uncorrected calcium ratio had the best fit to the citrate data with an R2 value of 0.39. The albumin-corrected calcium ratio, pH, anion gap (AG), albumin-corrected AG, standard base excess, and strong ion gap all had R2 values less than 0.05.

CONCLUSION(S)

In the absence of direct measurement of citrate concentration, uncorrected total-to-ionized calcium ratio is superior to other surrogate markers, though not ideal, in assessing citrate accumulation or toxicity.

Reduction in Hypercalcemia Following Readjustment of Target Serum 25-Hydroxy Vitamin D Concentration during Cholecalciferol Therapy in Vitamin D-Deficient Critically Ill Patients

The intent of this study was an evaluation of our effort to reduce the incidence of hypercalcemia in critically ill vitamin D-deficient patients with multiple traumatic injuries given cholecalciferol. Vitamin D deficiency was defined as a serum 25-hydroxy vitamin D concentration (25-OH vit D) of <20 ng/mL. Adult patients (>17 years of age) were given 10,000 IU of cholecalciferol daily with an intended target 25-OH vit D of >19.9 ng/mL. These patients were compared to a historical control group that underwent therapy with a higher target of >29.9 ng/mL. Patients received cholecalciferol via the feeding tube along with enteral nutrition (EN) until the target 25-OH vit D was achieved, EN discontinued, the nutrition support service signed off the patient, or the patient was discharged from the TICU. Patients were included if two consecutive weekly 25-OH vit D were measured. One hundred and three critically ill trauma patients were retrospectively studied. Fifty were given cholecalciferol therapy with the new lower target 25-OH vit D, and 53 were from a historical cohort aiming for the higher target. Hypercalcemia (serum ionized calcium concentration > 1.32 mmol/L) was reduced from 40% (21 out of 53 patients) to 4% (2 out of 50 patients; p < 0.001). None of the hypercalcemic patients were symptomatic. Readjustment of target 25-OH vit D concentration resulted in a ten-fold decrease in the rate of hypercalcemia and improved the safety of cholecalciferol therapy for critically ill patients with traumatic injuries.

Predicting ionized hypocalcemia: External validation of an ionized calcium prediction model in patients with COVID-19 and renal failure

Background

Ionized hypocalcemia is common in critically ill patients with COVID-19 and is associated with adverse outcomes. We previously developed a linear model that estimates ionized calcium (I_Ca) by adjusting total calcium (T_Ca) for the three components of the anion gap and albumin. On internal validation, it outperformed the popular method that corrects T_Ca for albumin alone (cT_Ca) in diagnosing low I_Ca. In this study, we sought to externally validate our I_Ca model in hospitalized COVID-19 positive patients.

Methods

We retrospectively studied all 200 patients with COVID-19 who were admitted to the State University of New York Downstate Medical Center between March 11^th and April 30^th 2020 and referred to the nephrology service for renal failure, and who had I_Ca measured on a venous blood gas within 25 min of a comprehensive metabolic panel. We compared the performance of the I_Ca model and cT_Ca in diagnosing low I_Ca by ROC analysis, and also examined the accuracy of the absolute values predicted by the two methods relative to measured I_Ca.

Results

On ROC analysis, the I_Ca model was better than cT_Ca (area under ROC curve: 0.872 [0.025] vs. 0.835 [0.028]; p = 0.045). The I_Ca model estimated I_Ca accurately, but the cT_Ca method seemed to overcorrect T_Ca, as a substantial number of patients with clearly normal cT_Ca values had low I_Ca.

Conclusions

In an external validation cohort, the I_Ca model estimated I_Ca accurately and was better than cT_Ca in the diagnosis of low I_Ca. This finding can be useful in guiding direct I_Ca testing.

Predicting Ionized Hypocalcemia in Critical Care: An Improved Method Based on the Anion Gap

BACKGROUND

Low ionized calcium (ICa) is prevalent in critical care patients. It is poorly detected by the popular indirect method, which corrects serum total calcium (TCa) for change in albumin. That correction (cTCa) ignores any concomitant change in the anion-complexed fraction of TCa. We tested whether the diagnosis of low ICa can be improved by further correcting for calcium complexation, represented by the anion gap (AG) or its components-sodium, chloride, and total carbon dioxide (tCO2).

METHODS

We retrospectively studied all patients in our intensive care units between 2009 and 2011 with ICa measured on arterial (n = 310) or venous (n = 462) gas panels within 19 min of a comprehensive chemistry panel. Logistic models to predict low ICa and linear models to estimate ICa were derived in the arterial group and validated in the venous group, using either AG (AG model) or its components (Ion model) as predictors, adjusted for TCa and albumin.

RESULTS

AG and its set of components were each highly significant independent predictors of low ICa. On validation, the logistic Ion model was better than the logistic AG model (ROC curve area ± SE: 0.92 ± 0.02 vs 0.89 ± 0.02; P = 0.008), which, in turn, was far better than cTCa (0.81 ± 0.03; P = 0.0006); the hypocalcemia rates predicted by the models showed good fit with the observed rates. Linear estimates of ICa were too imprecise for clinical use.

CONCLUSIONS

The adjustment of TCa for AG or for sodium, chloride, and tCO2 markedly improves the diagnosis of low ICa. This finding may be useful in guiding ICa testing.

Serum calcium improved systemic inflammation marker for predicting survival outcome in rectal cancer

Background

Systemic inflammation markers have shown prognostic values with variability in rectal cancer. Considering the association of serum calcium with inflammation, we aimed to examine whether it could improve systemic inflammation markers for survival prediction.

Methods

We enrolled 508 patients with stage I to III rectal cancer who underwent curative resection. The cohort was grouped by corrected serum calcium (cCa), platelet-to-lymphocyte ratio (PLR), and CaPLR (a score model combining cCa with PLR) for survival analysis. The LR (likelihood ratio) test and AIC (Akaike information criterion) were applied to compare models in survival prediction. The primary endpoint was disease-free survival (DFS).

Results

A total of 26.7% (136/508) patients reached recurrence after curative surgery. Both high cCa (HR 1.486; 95% CI, 1.018-2.171; P=0.040) and high PLR (HR 1.452; 95% CI, 1.059-1.991; P=0.021) were significantly associated with worse DFS. In model comparison, the AIC and LR were improved after cCa was added to PLR model in DFS prediction (AIC: 1,704.83 vs. 1,707.14 vs. 1,707.15; LR: 8.68 vs. 4.37 vs. 4.36; P=0.037). The CaPLR was developed for DFS prediction with adjusted HRs of 2.216 (95% CI, 1.256-3.909; P=0.006) and 1.679 (95% CI, 1.004-2.836; P=0.047) for high and intermediate score group respectively compared to low score group. A nomogram for predicting DFS was generated by using CaPLR and other clinical predictors, with a concordance index of 0.705 (95% CI, 0.620-0.789; P<0.001).

Conclusions

Serum calcium could improve systemic inflammation markers in survival prediction for patients with rectal cancer.

Serum Albumin Levels: Who Needs Them?

OBJECTIVES

The purpose of this critical narrative review is to discuss common indications for ordering serum albumin levels in adult critically ill patients, evaluate the literature supporting these indications, and provide recommendations for the appropriate ordering of serum albumin levels.

DATA SOURCES

PubMed (1966 to August 2020), Cochrane Library, and current clinical practice guidelines were used, and bibliographies of retrieved articles were searched for additional articles.

STUDY SELECTION AND DATA EXTRACTION

Current clinical practice guidelines were the preferred source of recommendations regarding serum albumin levels for guiding albumin administration and for nutritional monitoring. When current comprehensive reviews were available, they served as a baseline information with supplementation by subsequent studies.

DATA SYNTHESIS

Serum albumin is a general marker of severity of illness, and hypoalbuminemia is associated with poor patient outcome, but albumin is an acute phase protein, so levels vacillate in critically ill patients in conjunction with illness fluctuations. The most common reasons for ordering serum albumin levels in intensive care unit (ICU) settings are to guide albumin administration, to estimate free phenytoin or calcium levels, for nutritional monitoring, and for severity-of-illness assessment.

RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE

Because hypoalbuminemia is common in the ICU setting, inappropriate ordering of serum albumin levels may lead to unnecessary albumin administration or excessive macronutrient administration in nutritional regimens, leading to possible adverse effects and added costs.

CONCLUSIONS

With the exception of the need to order serum albumin levels as a component of selected severity-of-illness scoring systems, there is little evidence or justification for routinely ordering levels in critically ill patients.

Protein-bound calcium phosphate in uremic rat serum: a quantitative study

Protein-bound calcium (prCa) constitutes about 40% of serum total calcium, in which albumin is the most dominant protein. Given the chemical interaction between calcium and phosphate (Pi), the increased serum Pi in chronic kidney disease may cause changes in the composition and structure of the prCa fraction. Here, we report the phosphate binding on the protein-bound calcium in uremic rat serum. Using adenine-fed rats as a uremic model, we separated the calcium and phosphate fractions in rat serum by ultrafiltration, and found that the level of protein-bound phosphate (prPi) in the uremic serum was markedly higher than in control. The elevated prPi level was comparable to the prCa level, consistent with the presence of protein-bound calcium phosphate pr(Ca)_j-m(CaPi)_m. We then confirmed its presence by ex vivo X-ray absorption near-edge structure spectroscopy, revealing the discrete state of the calcium phosphate clusters associated with protein. Finally, in a quantitative investigation using Ca- and Pi-boosted serum, we discovered the threshold concentration for the Pi binding on prCa, and determined the binding constant. The threshold, while preventing Pi from binding to prCa in normal condition, allows the reaction to take place in hyperphosphatemia conditions. The protein-bound calcium phosphate could act as a link between the metabolism of serum proteins and the homeostasis of phosphate and calcium, and it deserves further investigation whether the molar ratio of (prPi/prCa)⋅100% may serve as a serum index of the vascular calcification status in chronic kidney disease.

Transfusion-Related Hypocalcemia After Trauma

BACKGROUND

Hypocalcemia is cited as a complication of massive transfusion. However, this is not well studied as a primary outcome in trauma patients. Our primary outcome was to determine if transfusion of packed red blood cells (pRBC) was an independent predictor of severe hypocalcemia (ionized calcium ≤ 3.6 mg/dL).

METHODS

Retrospective, single-center study (01/2004-12/2014) including all trauma patients ≥ 18 yo presenting to the ED with an ionized calcium (iCa) level drawn. Variables extracted included demographics, interventions, outcomes, and iCa. Regression models identified independent risk factors for severe hypocalcemia (SH).

RESULTS

Seven thousand four hundred and thirty-one included subjects, 716 (9.8%) developed SH within 48 h of admission. Median age: 39 (Range: 18-102), systolic blood pressure: 131 (IQR: 114-150), median Glasgow Coma Scale (GCS): 15 (IQR: 10-15), Injury Severity Score (ISS): 14 (IQR: 9-24). SH patients were more likely to have depressed GCS (13 vs 15, p < 0.0001), hypotension (23.2% vs 5.1%, p < 0.0001) and tachycardia (57.0% vs 41.9%, p < 0.0001) compared to non-SH patients. They also had higher emergency operative rate (71.8% vs 29%, p < 0.0001) and higher blood administration prior to minimum iCa [pRBC: (8 vs 0, p < 0.0001), FFP: (4 vs 0, p < 0.0001), platelet: (1 vs 0, p < 0.0001)]. Multivariable analysis revealed penetrating mechanism (AOR: 1.706), increased ISS (AOR: 1.029), and higher pRBC (AOR: 1.343) or FFP administered (AOR: 1.097) were independent predictors of SH. SH was an independent predictor of mortality (AOR: 2.658). Regression analysis identified a significantly higher risk of SH at pRBC + FFP administration of 4 units (AOR: 18.706, AUC:. 897 (0.884-0.909).

CONCLUSION

Transfusion of pRBC is an independent predictor of SH and is associated with increased mortality. The predicted probability of SH increases as pRBC + FFP administration increases.

Spontaneous neck hematoma secondary to parathyroid adenoma: a case series

PURPOSE

Spontaneous neck hematoma is a rare yet potentially fatal complication of primary hyperparathyroidism (PHPT). Here we aim to describe novel presentations of neck hematomas secondary to PHPT, discussing tools and signs that facilitate diagnosis.

METHODS

Case series data were extracted by retrospective chart reviews of our institution's electronic medical records, including all neck hematoma cases from parathyroid origin between 2005 and 2020. Cases from PubMed and EMBASE between 1999 and 2020 were analyzed in a systematic literature review.

RESULTS

Four patients were identified with five acute bleeding events, including a novel report of recurrent neck hemorrhage due to parathyroid adenoma. There was postmenopausal female predominance (75%), consistent with previous reports (72.7%). Common presentations included neck pain, dysphagia and hoarseness. All bleedings spread into the retropharyngeal space. Vocal cord paralysis was found in a single case and in 8.6% of the benign lesions in the reviewed cases. A single case presented with normal calcium levels (20% of bleeding episodes), in line with the reviewed cases (17.4%). A subtle CT sign of an enhancing area within the parathyroid gland, which led to the diagnosis, was identified in a single case. Conservative treatments were employed in 80% of our cases and in 51.5% of the reviewed cases, all being successful. Neck explorations performed after a 3-month waiting period from the acute event demonstrated better results compared to immediate surgery.

CONCLUSION

A high suspicion index is needed, particularly in post-menopausal women, to reach a diagnosis and allow optimal management. Normal laboratory values do not exclude parathyroid etiology, yet assessment should include calcium and PTH levels along with targeted imaging. Since bleeding may recur, we suggest that PHPT complicated with neck hematoma should be an independent indication for definitive parathyroidectomy surgery.

LEVEL OF EVIDENCE

3b.

Hypocalcemia in cancer patients: An exploratory study

Introduction

Calcium has several physiological functions and when it registers abnormal serum levels those functions may be impacted with potentially severe consequences. There is much research on hypercalcemia in cancer patients, but there are no recent studies on the prevalence of hypocalcemia in those patients. However, there has been an evolution in oncology, namely, new drugs that may directly or indirectly result in hypocalcemia. The primary aim was to explore the association of hypocalcemia with the diverse types of cancer. The secondary aim was to study the influence that hypocalcemia might have on survival.

Methods

Review of the records of patients ≥18 years old, with total calcium <2.0 mmol/L measured in 2013 in a cancer center.

Results

Eight hundred twenty-nine patients were included. Four hundred thirty-nine (53%) were male. The median age was 63 years. The most frequent cancer diagnoses were hematological 196 (24%) and colorectal 111 (13%). Six hundred thirty-eight patients had measured serum albumin, with a median of 25.5 g/L (14-47). When corrected for albumin level, calcium was in the normal range in 210 (33%) cases. The median survival of patients with corrected calcium lower than normal was 479 days (95% confidence interval [CI]: 309-649) and that of patients with normal corrected calcium was 62 days (95% CI: 33-91), P < .001. In a multivariate analysis, age, primary cancer, and albumin were significantly associated with survival.

Conclusion

Hypocalcemia is associated with several types of cancer. A low calcium level is not by itself a factor of a poor prognosis since other factors seem to be more important.

Hypercalcemia Without Hypervitaminosis D During Cholecalciferol Supplementation in Critically Ill Patients

BACKGROUND

Vitamin D deficiency during critical illness has been associated with worsened outcomes. Because most critically ill patients with severe traumatic injuries are vitamin D deficient, we investigated the efficacy and safety of cholecalciferol therapy for these patients.

METHODS

Fifty-three patients (>17 years of age) admitted to the trauma intensive care unit who had a serum 25-hydroxy vitamin D (25-OH vit D) concentration <20 ng/mL were given 10,000 IU of cholecalciferol daily. Efficacy was defined as achievement of a 25-OH vit D of 30-79.9 ng/mL. Safety was evaluated by the presence of hypercalcemia (serum ionized calcium [iCa] >1.32 mmol/L) or hypervitaminosis D (25-OH vit D >79.9 nmol/L). Patients were monitored for 2 weeks during cholecalciferol therapy.

RESULTS

Twenty-four patients (45%) achieved target 25-OH vit D. No patients experienced hypervitaminosis D. Hypercalcemia occurred in 40% (n = 21) of patients; 2 patients experienced an iCa >1.49 nmol/L. 25-OH vit D was significantly greater for those who developed hypercalcemia (37.2 + 11.2 vs 28.4 + 5.6 ng/mL, respectively, P < 0.001) by the second week of cholecalciferol. Of 24 patients who achieved target 25-OH vit D, 14 (58%) experienced hypercalcemia in contrast to 24% of patients (7 out of 29) who did not achieve target 25-OH vit D (P = 0.024).

CONCLUSIONS

Cholecalciferol normalized serum 25-OH vit D concentrations in less than half of patients yet was associated with a substantial proportion of patients with hypercalcemia without hypervitaminosis D.

Cost-effectiveness in transient hypocalcemia post-thyroidectomy

BACKGROUND

Three different strategies to manage transient hypocalcemia after total thyroidectomy were compared to evaluate cost-effectiveness. The reliability of total serum calcium (TSCa), ionized calcium (ICa), and intact parathyroid hormone (iPTH) were investigated to achieve this goal.

METHODS

A multicenter, prospective randomized study was carried out with 169 patients. The strategies were "preventive" (oral calcium + vitamin D supplementation), "reactive" (therapy in hypocalcemia), and "predictive" (therapy if iPTH <10 pg/mL).

RESULTS

TSCa had higher accuracy in identifying patients who developed hypocalcemia-related symptoms than ICa (84.6% vs 50.0%). TSCa 24 h after surgery showed 24.8% of patients with hypocalcemia, whereas TSCa 48 h after surgery identified a further 10.6% with hypocalcemia (only in the "reactive" and "predictive" groups). iPTH showed low sensitivity as a predictor of hypocalcemia. Between the 3 groups, there was no significant difference in hospitalization time or number of symptomatic hypocalcemic patients. Interestingly, the cost-per-patient was significantly different among the groups.

CONCLUSIONS

None of the discussed strategies allowed for early discharge of patients without any risk of transient hypocalcemia. The "preventive" strategy was the most cost-effective, despite overtreatment.

Obesity attenuates serum 25-hydroxyvitamin D response to cholecalciferol therapy in critically ill patients

OBJECTIVES

The presence of obesity may confound cholecalciferol dosing in vitamin D-deficient patients owing to potentially decreased bioavailability. The aim of this retrospective study was to evaluate cholecalciferol therapy in vitamin D-deficient, critically ill trauma patients with and without obesity.

METHODS

Adult patients with severe traumatic injuries who had a serum 25-hydroxyvitamin D (25-OH vit D) <50nmol/L were prescribed 10 000 IU of liquid cholecalciferol daily. Efficacy was defined as achievement of a 25-OH vit D of 75 to 200nmol/L. Safety was evaluated by the presence of hypercalcemia (serum ionized calcium >1.32 mmol/L). Fifty-three patients (18 obese, 35 non-obese) were identified for study.

RESULTS

Despite similar baseline concentrations (36 ± 7 versus 37 ± 7 nmol/L; P = NS), 25-OH vit D response was attenuated for those with obesity after 1 and 2 wk of cholecalciferol therapy (51 ± 18 versus 66 ± 27nmol/L, P < 0.01; 68 ± 19 versus 92 ± 25nmol/L, P < 0.01, respectively). Patients with obesity also tended to experience less hypercalcemia (22% versus 49% of patients, respectively) post-cholecalciferol therapy.

CONCLUSION

Obesity alters the response to cholecalciferol therapy in critically ill patients with severe traumatic injuries.

Misclassification of Calcium Status Based on Albumin-Adjusted Calcium: Studies in a Tertiary Hospital Setting

BACKGROUND

Clinical laboratories measure total calcium and adjust for albumin concentrations to predict calcium status. We compared total and adjusted calcium (Adj-Ca) with ionized calcium (Ca2+) for correct assignment of calcium status. The effect of restriction of Adj-Ca reporting in patients with hypoalbuminemia was determined on the basis of frequency of misclassifications.

METHODS

Extraction of laboratory results was performed for 24 months. Adj-Ca was calculated from a modified Payne formula. A further prospective data set for 6 months was collected after stopping reporting of Adj-Ca for patients with an albumin &lt;3.0 g/dL. The agreement between Ca2+ and Adj-Ca or total Ca was assessed with Cohen's kappa statistic.

RESULTS

In 5553 hospitalized patients, 13604 paired Ca2+ results were analyzed retrospectively. Prospective collection in 1113 paired samples was from 450 patients. Adj-Ca was a poor predictor of calcium status compared to the Ca2+ reference standard in both data sets (agreement 56.9% in the first, 65.6% in the second data set). Renal failure and low albumin concentrations were associated with worse agreement between Adj-Ca and Ca2+. Restriction of reporting of Adj-Ca to albumin concentrations &gt;3.0g/dL improved correct classification of calcium status from 65.6% to 77.6% (P &lt; 0.0001). Total Ca performed better than Adj-Ca for low albumin (&lt;3.0g/dL) and performed similarly in samples with albumin &gt;3.0g/dL.

CONCLUSIONS

Adj-Ca is unreliable for the classification of calcium status in hospital patients when compared to Ca2+. Adj-Ca overestimates calcium for patients with renal impairment and albumin concentrations &lt;3.0g/dL. Restriction of reporting Adj-Ca for albumin below 3.0 g/dL reduces the number of misclassified patients.

Increase of endocan, a new marker for inflammation and endothelial dysfunction, in acute kidney injury

OBJECTIVE:

In this study, the clinical relevance of the levels of serum endocan and 25-hydroxyvitamin D [25(OH)D] was investigated in patients with acute kidney injury (AKI). Endocan or the endothelial cell-specific molecule 1 is a soluble proteoglycan secreted by vascular endothelial cells. It plays a significant role in immunity, inflammation, and endothelial function.

METHODS:

A total of 39 patients with AKI (19 females, 20 males) and 38 healthy individuals (18 females, 20 males) were included in the study. The levels of serum endocan, vitamin D, and other biochemical parameters were compared between the two groups.

RESULTS:

In the AKI group, the values of serum creatinine, endocan, parathormone, phosphorus, and uric acid were found to be higher, and the total protein, albumin, and calcium levels were lower compared to the control group. There was no difference between the two groups in terms of the serum vitamin D, magnesium, alkaline phosphatase, and gamma-glutamyl transferase.

CONCLUSION:

In patients with AKI, an increased endocan level is a significant marker of inflammation and endothelial injury. In addition, these patients experience vitamin D deficiency.

Predictive accuracy of serum total calcium for both critically high and critically low ionized calcium in critical illness

BACKGROUND

The accuracy of total calcium and its corrected value for predicting critically high and critically low ionized calcium in critical illness is controversial. The aim of this study was to investigate whether the concentration of total serum calcium, either corrected for albumin or not, could predict critically high or low values in critical illness.

METHODS

This report describes a retrospective study using the Medical Information Mart for Intensive Care (MIMIC) III database. Test panels that contained serum albumin, total calcium, and ionized calcium (named ATI panels) with order time intervals of less than one hour were extracted. The predictive accuracy of total calcium, either corrected for albumin or not, was assessed using receiver operating characteristic (ROC) curve analysis.

RESULTS

A total of 12 118 ATIs with 103 critically low and 92 critically high ionized calcium results were extracted. The areas under ROC curves (AUCs) of corrected and uncorrected total calcium for predicting critically low ionized calcium were 0.69 (95% CI: 0.61-0.76) and 0.70 (95% CI: 0.63-0.78), respectively. For predicting critically high ionized calcium, the AUCs were 0.98 (95% CI: 0.97-1.00) and 0.97 (95% CI: 0.95-1.00), respectively. With positive predictive values (PPVs) of 0.05 and 0.10, the sensitivities (both corrected and uncorrected) were approximately 0.50 for predicting critically low ionized calcium and 0.95 for predicting critically high ionized calcium.

CONCLUSIONS

Total calcium, either corrected for albumin or not, is not a reliable test to predict critically low ionized calcium in critical illness. Total calcium's predictive accuracy for critically high ionized calcium is high.

Association Between Disease Severity and Calcium Concentration in Critically Ill Patients Admitted to Intensive Care Unit

Background

Hypocalcemia is very common in critically ill patients admitted to ICU. However, its clinical importance and relation to patient’s outcome during early days of ICU admission is questionable. Based on the mentioned problem, it seems that calcium assessment is highly important in these patients. The present study aimed at evaluating the relationship between different calcium concentrations (total/ionized/corrected) and disease severity in critically ill patients.

Methods

A total of 100 patients admitted to intensive care units of Imam Reza and Shohada hospitals during Feb 2014 and Apr 2016 were enrolled in this prospective trial. Concentrations of total, corrected, and ionized calcium and their relationship with APACHE score and disease severity were noted during the study.

Results

There was a strong and inverse correlation between disease severity and ionized calcium concentration (P < 0.001, r = -0.697). There was a medium and significant inverse correlation between disease severity and total calcium concentration (P < 0.001, r = -0.368). Weak and direct significant correlation was observed between disease severity and corrected calcium concentration (P 0.02, r = 0.232).

Conclusions

A significant correlation was found between total and ionized calcium, but there was not any significant correlation between corrected and ionized calcium. Hypocalcemia is a predictor of disease severity and mortality. We recommend measuring ionized calcium concentration for patients admitted to ICU.

Comparison of pre-filter and post-filter ionised calcium monitoring in continuous veno-venous hemodiafiltration (CVVHD-F) with citrate anti-coagulation

Background

It is widespread practice during citrate anticoagulated renal replacement therapy to monitor circuit ionised calcium (iCa²⁺) to evaluate the effectiveness of anticoagulation. Whether the optimal site to sample the blood path is before or after the haemofilter is a common question.

Methods

Using a prospectively collected observational dataset from intensive care patients receiving pre-dilution continuous veno-venous haemodiafiltration (CVVHD-F) with integrated citrate anticoagulation we compared paired samples of pre and post filter iCa²⁺ where the target range was 0.3–0.5 mmol.L^-1 as well as concurrently collected arterial iCa²⁺. Two nested mixed methods linear models were fitted to the data describing post vs pre filter iCa²⁺, and the relationship of pre, post and arterial samples.

Setting

An 11 bed general intensive care unit.

Participants

450 grouped samples from 152 time periods in seven patients on CRRT with citrate anticoagulation.

Results

The relationship of post to pre-filter iCa²⁺ was not 1:1 with post = 0.082 + 0.751 x pre-filter iCa²⁺ (95% CI intercept: 0.015–0.152, slope 0.558–0.942). Variation was greatest between patients rather than between circuits within the same patient or citrate dose. Compared to arterial iCa²⁺ there was no significant difference between pre and post-filter sampling sites (F-value 0.047, p = 0.827)

Conclusion

These results demonstrate that there is minimal difference between pre and post filter samples for iCa²⁺ monitoring of circuit anticoagulation in citrate patients relative to the arterial iCa²⁺ in CVVHD-F however compared to pre-filter sampling, post filter sampling has a flatter response and greater variation.

Outcomes associated to serum phosphate levels in patients with suspected acute coronary syndrome

BACKGROUND

We investigated the association between phosphate and the risk of adverse clinical outcomes in patients with manifest cardiovascular disease (CVD).

METHODS

Observational study of patients hospitalized during 2006-2011 in Stockholm, Sweden, because of suspected acute coronary syndrome (ACS). The exposure was serum phosphate during the hospitalization. We modeled the association between phosphate and in-hospital death or in-hospital events (composite of myocardial infarction, cardiogenic shock, resuscitated cardiac arrest, atrial fibrillation, or atrioventricular block) as well as the one-year post-discharge risk of death or cardiovascular event (composite of myocardial re-infarction, heart failure and stroke). Confounders included demographics, comorbidities, kidney function, diagnoses, in-hospital procedures and therapies.

RESULTS

Included were 2547 patients (68% men, mean age 67±14years) with median phosphate of 1.10 (range 0.14-4.20) mmol/L. During hospitalization, 198 patients died and 328 suffered an adverse event. Within one year post-discharge, further 381 deaths and 632 CVD events occurred. The associations of phosphate with mortality and CVD were J-shaped, with highest risk magnitudes at higher phosphate levels. For instance, compared to patients in the 50th percentile of phosphate distribution, those above the 75th percentile (1.3mmol/L, normal range) had significantly higher odds for in-hospital death [odds ratio 1.36, 95% confidence interval (CI) (1.08-1.71)] and of CVD post-discharge [sub-hazard ratios 1.17 (1.03-1.33)].

CONCLUSIONS

In patients with suspected ACS, both higher and lower phosphate levels associated with increased risk of adverse outcomes during the index hospitalization and within one year post-discharge. The risk association was present already within normal-range serum phosphate values.

Albumin adjustment of total calcium does not improve the estimation of calcium status

BACKGROUND

There is a longstanding controversy as to whether plasma measurements of total calcium should be adjusted for albumin concentration, and if so which formulas are the most appropriate.

METHODS

Ionised calcium, total calcium and albumin results, analysed at the same time at Uppsala University Hospital Laboratory between February 2005 and June 2013, were retrieved from a laboratory information system. The dataset included results from 20,003 patients. Total calcium was albumin-modified by a locally derived formula, based on 3106 patients from the dataset, and formulas from the literature. The agreement between the reference method ionised calcium and unadjusted total calcium and the seven different albumin-modifying calcium formulas, respectively, were compared with intra-class correlation coefficients (ICC).

RESULTS

Total calcium showed substantial agreement to ionised calcium, ICC 0.85 (95% CI 0.84-0.86) for the whole validation cohort. Albumin-modified calcium by different formulas showed significantly less or equal agreement, however the locally determined formula performed better than formulas taken from the literature. Also, total calcium classified the patient as hypo-normo- or hypercalcemic right in 82% of the patients. The albumin-modified calcium did not classify patients significantly better except in the subgroup hypoalbuminemia (<30 g/L) where the local formula classified the patients slightly better than total calcium.

CONCLUSIONS

Albumin modification of total calcium determinations is unlikely to add valuable information, and this practice should be abandoned. Ionised calcium should be used more frequently when aberrant results for total calcium are followed up, or in patients with known hypoalbuminemia.

Association Between Serum Calcium Level and Extent of Bleeding in Patients With Intracerebral Hemorrhage

Importance

Calcium is a key cofactor of the coagulation cascade and may play a role in the pathophysiology of intracerebral hemorrhage (ICH).

Objective

To investigate whether a low serum calcium level is associated with an increase in the extent of bleeding in patients with ICH as measured by baseline hematoma volume and risk of hematoma expansion.

Design, Setting, and Participants

Prospective cohort study of 2103 consecutive patients with primary ICH ascertained during the period between 1994 and 2015 at an academic medical center. The statistical analysis was performed in January 2016.

Main Outcomes and Measures

Total calcium level was measured on admission, and hypocalcemia was defined as a serum calcium level of less than 8.4 mg/dL. Baseline and follow-up hematoma volumes, detected by noncontrast computed tomography, were measured using a computer-assisted semiautomatic analysis. Hematoma expansion was defined as an increase of more than 30% or 6 mL from baseline ICH volume. Associations between serum calcium level and baseline hematoma volume and between serum calcium level and ICH expansion were investigated in multivariable linear and logistic regression models, respectively.

Results

A total of 2123 patients with primary ICH were screened, and 2103 patients met the inclusion criteria (mean [SD] age, 72.7 [12.5] years; 54.3% male patients), of whom 229 (10.9%) had hypocalcemia on admission. Hypocalcemic patients had a higher median baseline hematoma volume than did normocalcemic patients (37 mL [IQR, 15-72 mL] vs 16 mL [IQR, 6-44 mL]; P < .001). Low calcium levels were independently associated with higher baseline ICH volume (β = -0.13, SE = .03, P < .001). A total of 1393 patients underwent follow-up noncontrast computed tomography and were included in the ICH expansion analysis. In this subgroup, a higher serum calcium level was associated with reduced risk of ICH expansion (odds ratio, 0.55 [95% CI, 0.35-0.86]; P = .01), after adjusting for other confounders.

Conclusions and Relevance

Hypocalcemia correlates with the extent of bleeding in patients with ICH. A low calcium level may be associated with a subtle coagulopathy predisposing to increased bleeding and might therefore be a promising therapeutic target for acute ICH treatment trials.

Significance of the ionized calcium measurement to assess calcium status in osteopenic/osteoporosis postmenopausal outpatients

INTRODUCTION

Evaluation of calcium status is important in the osteoporotic risk assessment. Although guidelines indicate total calcium (tCa) as first-line measurement, directly measured ionized calcium (m-iCa), considered as the gold standard, is more and more often required. Aim of this study is to evaluate the agreement between m-iCa, tCa and iCa calculated from a formula based on total calcium and albumin (c-iCa) in osteopenic/osteoporotic postmenopausal outpatients.

METHODS

A total of 140 postmenopausal outpatients, 41 osteopenic (OPN) and 99 osteoporotic (OP) were enrolled. Levels of tCa, m-iCa, c-iCa, total protein and albumin, vitamin D (25-OHD), parathyroid hormone 1-84 (PTH), bone alkaline phosphatase, osteocalcin and serum collagen type 1 cross-linked C-telopeptide (CTX) were also measured.

RESULTS

There were no statistically significant differences between OPN and OP groups regarding values of tCa, m-iCa, and c-iCa, 25-OHD and PTH. However, OP women had lower levels of CTX (p < 0.05). A significant direct correlation between m-iCa and tCa (r = 0.60, p < 0.001) and c-iCa (r = 0.61, p < 0.001) was found. Women with isolated hyper-m-iCa had similar DEXA parameter levels respect to the other patients. However, one patient with confirmed primary hyperparathyroidism presented hyper-m-iCa versus normal tCa and c-iCa values.

CONCLUSIONS

The use of tCa could be sufficient to characterize the calcium status in postmenopausal outpatients, but reflexive calcium testing strategy for m-iCa test is necessary to women presenting the low or high extremes of tCa levels, or in women with suspected PHPT.

A New Graduated Dosing Regimen for Phosphorus Replacement in Patients Receiving Nutrition Support

BACKGROUND

Hypophosphatemia is a common metabolic complication in patients receiving specialized nutrition support. We changed our previously reported dosing algorithm because the low dose no longer appeared to be effective at increasing serum phosphorus concentrations. The purpose of this study was to evaluate the safety and efficacy of a revised weight-based phosphorus-dosing algorithm in critically ill trauma patients receiving specialized nutrition support.

METHODS

Seventy-nine adult trauma patients with hypophosphatemia (serum phosphorus concentration < or = 0.96 mmol/L) receiving nutrition support received an IV dose of phosphorus on day 1 according to the serum concentration of phosphorus: 0.73-0.96 mmol/L (0.32 mmol/kg, low dose), 0.51-0.72 mmol/L (0.64 mmol/kg, moderate dose), and < or = 0.5 mmol/L (1 mmol/kg, high dose). The IV phosphorus bolus dose was administered at 7.5 mmol/hour. Generally, patients with a serum potassium concentration <4 mmol/L received potassium phosphate and patients with a serum potassium concentration > or = 4 mmol/L received sodium phosphate. Patients who still had hypophosphatemia on day 2 were dosed using the new dosing algorithm by the nutrition support service according to that day's serum concentration of phosphorus, or empirically by the trauma service.

RESULTS

Of the 79 patients studied, 57 were male and 22 were female with a mean age of 44.8 +/- 20.6 years. Mean Injury Severity Scores and APACHE-II scores were 27.1 +/- 11.6 and 15.2 +/- 6.8, respectively. There was no difference in baseline characteristics among the 3 dosing groups. Of the 79 patients, 34 received the low dose, 30 received the moderate dose, and 15 received the high dose of phosphorous. Mean serum phosphorous concentrations on day 2 were significantly increased in the moderate-dosed group (0.64 +/- 0.06 to 0.77 +/- 0.22 mmol/L, p < .05) and high-dosed group (0.38 +/- 0.06 to 0.93 +/- 0.32 mmol/L, p < .01), respectively, when compared with day 1. Mean serum phosphorus concentrations were normal in all 3 groups on day 3. Serum concentrations of magnesium, sodium, and potassium, as well as arterial pH, were stable across the study. Mean concentrations of ionized calcium were not significantly different in any of the 3 dosing groups across the study period.

CONCLUSIONS

This weight-based phosphorus-dosing algorithm is safe for use in critically ill patients receiving nutrition support. The moderate and severe-dose regimens effectively increase serum phosphorus concentrations.

Association of Insulin Resistance, β-Cell Function Impairment and Calcium, Magnesium, and Fetuin-A Concentrations in Women with Type 2 Diabetes Mellitus

Insulin resistance and β-cell function impairment play a role in the pathogenesis of type 2 diabetes (T2DM). Insulin signaling is inhibited by fetuin-A, an abundant plasma protein. Fetuin-A is also a candidate marker of the T2DM risk. This case-control study aimed to determine whether fetuin-A serum level is related to insulin resistance, β-cell function impairment, and total and ionized Ca and Mg serum levels in Erbil patients with T2DM.

A total of 60 patients with T2DM were recruited, and 30 healthy persons were included in the control group. Fetuin-A and insulin concentrations were measured through ELISA. Other biochemical parameters were determined spectrophotometrically. Insulin resistance (HOMA2IR), insulin sensitivity (HOMA2%S), and β-cell function were examined by using a homeostatic model assessment 2 (HOMA2).

Fasting serum insulin, fetuin-A serum levels, and HOMA2IR were significantly increased. HOMA2%S of the patients with diabetes was significantly lower than that of the control group. The total serum and ionized Ca and Mg contents and the Ca/Mg ratio were reduced in the patients.

Therefore, fetuin-A is related to T2DM pathogenesis and is strongly associated with insulin resistance and glycemic control in T2DM patients. Future large-scale studies are necessary to validate fetuin-A as an indicator of IR in T2DM patients.

Comparison Between Measured and Calculated Free Calcium Values at Different Serum Albumin Concentrations

INTRODUCTION

Free ionic calcium is the metabolically active component of total calcium (TCa) in blood. However, most laboratories report TCa levels that are dependent on serum albumin concentration. Hence, several formulae have evolved to calculate free calcium levels from TCa after adjustment for albumin. However, free calcium can directly be measured using direction selective electrodes rather than spectrophotometric methods used in autoanalyzers.

OBJECTIVES

This study compares the levels of free calcium obtained by measurement by direct ion selective electrode (ISE) and the one calculated as a function of TCa by formulae.

MATERIALS AND METHODS

A total of 254 serum samples submitted to clinical biochemistry laboratory of a tertiary care hospital were analyzed for total protein, albumin, and TCa by standard spectrophotometric methods and for free calcium by direct ISE. Three commonly used formulae viz. Orrell, Berry et al. and Payne et al. were used to calculate adjusted TCa. Calculated free calcium was obtained by taking 50% of these values.

RESULTS

A significant difference (P < 0.05) was observed between calculated free calcium by all the three formulae and measured free calcium estimated by direct ISE using paired t-test and Bland-Altman plots.

CONCLUSION

Formulae for predicting free calcium by estimating TCa and albumin lacks consistency in prediction and free calcium should be evaluated by direct measurement.

New Predictive Equations for Serum Ionized Calcium in Hospitalized Patients

OBJECTIVE

To study a new and easy way to calculate equations to predict ionized calcium (Ca2+) for adult hospitalized patients with the usual laboratory and clinical parameters.

SUBJECTS AND METHODS

This retrospective observational study was conducted in a third-level university hospital. An initial learning cohort (cohort L: 269 patients) was selected to derive the new equations. These equations were tested in a validation of another cohort (cohort V: 146 patients). Patients selected were hospitalized adults who had simultaneous determinations of Ca2+ and serum total calcium (CaTot). They were classified using their estimated glomerular filtration rate (GFRe) into normal function, moderate and severe kidney dysfunction. Demographic and biochemical parameters, in addition to comorbidities, were collected from hospital databases. Nine published equations to predict Ca2+ and 2 widely used equations to predict corrected CaTot were also selected to be compared to newer equations for accuracy in detecting serum calcium alterations. New equations were derived by a multiple linear-regression analysis from patients in cohort L.

RESULTS

Three equations were derived containing the CaTot square root as the main independent variable. Equation 1: Ca2+ = 0.815 × CaTot(0.5). Equation 2: Ca2+ = 0.826 × CaTot(0.5) - 0.023 × renal function. Equation 3: Ca2+ = 0.813 × CaTot(0.5) - 0.006 × albumin(0.75) + 0.079. These equations performed better than published equations to predict Ca2+ when their error measures were analyzed in cohort V, even in special populations such as critically ill and very old patients.

CONCLUSIONS

Three new equations predicting Ca2+ were derived requiring easily available clinical and laboratory parameters. They could be valuable in predicting hypocalcemia but are of limited use in hypercalcemia.

Proteinuria as the Most Relevant Parameter Affecting Fetuin-A Levels in Preeclampsia

The present study aimed to examine the factors affecting the possible changes in serum fetuin-A in patients with preeclampsia (PE). The examined factors included the parameters of insulin resistance (IR) [(insulin sensitivity (HOMA%S), insulin resistance (HOMA2IR), and beta-cell functions (HOMA%B)], which were calculated using the HOMA2 calculator, and total and ionized calcium and magnesium levels.

Sixty PE patients and thirty healthy pregnant women, which comprised the study group and control group, respectively participated in the present study. Fetuin-A, estradiol, insulin, glucose, total and ionized calcium and magnesium, total protein, albumin, and globulins were measured in their sera.

The results of the present study showed that serum total and ionized magnesium and the I.Ca/Mg ratio decreased in PE women. Although the fasting insulin level and HOMA2IR were higher and HOMA2%S was lower in PE compared with the control women, PE did not appear as an overt insulin-resistant state. Serum fetuin-A was low in PE patients compared with the control group because PE women had proteinuria. Fetuin-A levels were not correlated with the characteristics and IR parameters, cations, and estradiol levels, but it was correlated with the severity of proteinuria.

These results confirmed the hypothesis that proteinuria results in the loss of fetuin-A because it has a low molecular weight.

Nutritional status, assessment, requirements and adequacy of traumatic brain injury patients

Traumatic Brain Injury (TBI) has been considered as a serious public health problem. Each year, traumatic brain injuries are contributing to a substantial number of cases of permanent disability and deaths and it can be classified according to the severity into penetrating and closed head injury. Symptoms, beside to be unconscious can be defined as vomiting, nausea, headache, dizziness, lack of motor coordination, difficulty in balancing, blurred vision and lightheadedness, bad taste in the mouth, ringing in the ears, fatigue and lethargy as well as changes in sleep patterns. The brain is known to be the functional regulator for all the metabolic activities inside the body and TBI patients mostly have a complex metabolic alterations including aberrant cellular metabolism, abnormal metabolic processes, changes in hormones functions and inflammatory cascade. The TBI patient's status needed to be assessed medically and nutritionally since the medical status of the patients can affect the nutrition part. Data from the four assessment tools are needed to be correctly used and interpreted in order to make a proper nutritional diagnosis, clinical assessment, biochemistry as well as anthropometric measurements. Regardless the methods used for assessing TBI patients, having adequate intake and medical care can lead to a reduction in hospital costs, numbers of day hospitalized, numbers of hours of mechanical ventilation and in the overall infection rates.

Dose-response effect of ergocalciferol therapy on serum 25-hydroxyvitamin D concentration during critical illness

OBJECTIVE

The aim of this study was to evaluate the dose-response relationship between ergocalciferol therapy and serum 25-hydroxyvitamin D concentrations in enterally fed, critically ill patients with traumatic injuries.

METHODS

A retrospective cohort of critically ill patients with traumatic injuries and vitamin D deficiency (25-OH vitamin D <50 nmol/L) were given either 50 000 IU of liquid ergocalciferol weekly, twice weekly, or three times weekly while in the intensive care unit (ICU). Serum 25-OH vitamin D and ionized calcium concentrations were monitored weekly. Ergocalciferol therapy was stopped when the serum 25-OH vitamin D was >75 nmol/L, if the patient experienced hypercalcemia (ionized calcium >1.34 mmol/L), when the patient was discharged from the ICU, or if enteral nutrition was discontinued.

RESULTS

Sixty-five patients (16, 18, and 31 per dosage group) were examined. One (6%), two (11%), and eight (26%) patients achieved normal 25-OH vitamin D concentrations after 2 to 4 wk of ergocalciferol therapy for each dosage group, respectively (P < 0.001). Serum 25-OH vitamin D concentrations improved from 36 ± 6, 40 ± 7, and 37 ± 6 nmol/L to 50 ± 15, 54 ± 21, and 62 ± 17 nmol/L, respectively, after 2 wk of ergocalciferol therapy (P < 0.001) Two (13%), one (6%), and seven (23%) patients developed hypercalcemia for each dosage group, respectively (P = NS).

CONCLUSIONS

Ergocalciferol therapy improved baseline serum 25-OH vitamin D concentrations but was inadequate for consistently achieving normal serum concentrations of 25-OH vitamin D during critical illness. The trend in increasing appearance of mild hypercalcemia for the highest dosage group is concerning.

Phosphorus and calcium: a review for the adult nutrition support clinician

Phosphorus (P) and calcium (Ca) serve vital roles in the human body and are essential components of nutrition support therapy. Regulation of P and regulation of Ca in the body are closely interrelated, and P and Ca homeostasis can be affected by several factors, including disease states, clinical condition, severity of illness, and medications. Nutrition support clinicians must understand these factors to prevent and treat P and Ca disorders in patients receiving nutrition support therapy. This review provides an overview of P and Ca for the adult nutrition support clinician, with some emphasis on the hospitalized inpatient.

Calcium intake and serum calcium status in Mongolian children

Dietary calcium intake in relation to calcium status in Mongolian children was investigated. This survey was a cross-sectional survey. A total of 835 children were randomly selected from 4 economic regions and Ulaanbaatar city. Information on dietary intake was collected from 835 children in the 1-3, 4-7, and 8-14 year old groups by a 24-h recall method. The average daily intake of calcium from diet was calculated for individuals. Blood samples were collected from 104 children. The mean of daily calcium intakes as 273±30.0mg in 1-3-year old children, 309.0±30.0mg in 4-7 year old children, and 317.0±31.0mg in 8-14 year old children, respectively. There were statistically significant differences in calcium intakes between the age groups 1-3 years, 4-7 years, and 1-3 years, 8-14 years of children (p<0.001). Calcium intakes in all studied children of all age groups were lower (39%, 30.9%, and 24.4%) than the recommended level of calcium intakes. In 22.1% of studied children, the serum total calcium concentration levels were below the normal range. Based on the total serum calcium, the prevalence of hypocalcemia was higher among children in the age group 8-14 years (27.6%) than the prevalence among children in the age group <1 year (p<0.05). Based on the corrected serum calcium values, the prevalence of hypocalcemia was higher (52.4%, 63.6%, and 51.1%) among children in the age groups 1-3, 4-7, and 8-14 years. The mean level of corrected serum calcium were low (2.02±0.04, 2.05±0.73, and 1.99±0.64mg) in children in the age groups 1-3, 4-7, and 8-14 years. These findings suggest that low dietary calcium intakes may be reflected by hypocalcemia in Mongolian children. In conclusion, there is a need to improve a consumption of milk, dairy products in Mongolian children. In addition, there is need to use a vitamin D supplementation with a calcium supplementation in children with severe vitamin D deficiency rickets. This article is part of a Special issue entitled "16th Vitamin D Workshop".

[Total serum calcium and corrected calcium as severity predictors in acute pancreatitis]

OBJECTIVES

To evaluate total serum calcium (TC) and albumin-corrected calcium (ACC) as prognostic severity factors in acute pancreatitis (AP).

METHODS

Ninety-six patients were included in the study. They were diagnosed with AP and admitted to the Hospital Regional de Veracruz within the time frame of January 2010 to December 2012. AP severity was determined through the updated Atlanta Classification (2013). TC and ACC values were measured in the first 24hours of admittance and the percentages of sensitivity (S), specificity (Sp), positive predictive value (PPV), negative predictive value (NPV), positive likelihood ratio (LR+), and negative likelihood ratio (LR-) were calculated through ROC curves and contingency tables.

RESULTS

In accordance with the updated Atlanta Classification, 70 patients presented with mild AP, 17 with moderately severe AP, and 9 with severe AP. Of the patient total, 61.5% were women, and 69.8% presented with biliary etiology. The maximum TC cut-off point was 7.5mg/dL, with values of S, 67%; Sp, 82%; PPV, 27%, and NPV, 96%. The maximum ACC cut-off point was 7.5mg/dL, with values of S, 67%; Sp, 90%; PPV, 40%; NPV, 96%. Both had values similar to those of the Ranson and APACHE II prognostic scales.

CONCLUSIONS

TC and ACC, measured within the first 24hours, are useful severity predictors in acute pancreatitis, with sensitivity and predictive values comparable or superior to those of the conventional prognostic scales.

Effect of cholecalciferol recommended daily allowances on vitamin D status and fibroblast growth factor-23: an observational study in acute burn patients

OBJECTIVE

Burn patients are at risk of hypovitaminosis D. Optimal vitamin D (VD) intakes are not defined in burn nutrition guidelines and studies mostly focused on ergocalciferol (VD2) supplementation in burn children. Aim of our study was to describe adult burns VD status, to measure effects of our cholecalciferol (VD3) supplementation on VD metabolism during acute burn care, and to assess correlation between FGF23 and C-reactive protein (CRP).

DESIGN

Cohort study.

METHODS

From March 2012 to January 2013, patients >18 years, admitted within 24 h after injury with burn surface area (BSA) ≥10% were included. Patients daily received VD3 from oral or enteral nutrition (400-600 IU) and from oral or intravenous multivitamin complex (200-220 IU). Serum levels of 25(OH)-D, 1-25(OH)2-D, 3rd generation PTH, C-terminal FGF23, total calcium, phosphate, albumin and CRP were measured at admission (D0) and every week during 4 weeks of follow-up. Data are expressed as percentage or median (min-max). Paired data were compared using Wilcoxon test. Correlation between CRP and FGF23 was assessed using nonparametric Spearman test. A p value <0.05 was considered to be statistically significant.

RESULTS

We initially included 24 patients. Median age and BSA were, respectively, 46 [19-86] years and 15 [10-85]%. At D0, 75% presented a VD insufficiency (25(OH)-D 21-29 ng/ml) and 17% presented a deficiency (25(OH)-D ≤20 ng/ml). We followed 12 patients until day 28: 25(OH)-D was unchanged while 1-25(OH)2-D and FGF23 decreased without reaching significance. We observed a significant positive correlation between FGF23 and CRP (r=0.59, 95% CI: 0.22-0.82, p=0.0032).

CONCLUSIONS

Most of our adult burns presented hypovitaminosis D regardless of age. Nutrition supplemented with low dose of VD3 (intakes reaching recommended daily allowances) was insufficient to correct 25(OH)-D level. Moreover, an interesting correlation between CRP and FGF23 was found.