Discrepancies in corrected calcium versus ionised calcium in a geriatric population: an observational study.

BACKGROUND: Calcium can be measured as ionised (Ca-ionised) or albumin-adjusted total calcium (Ca-albumin). Current clinical guidelines predominantly utilise Ca-albumin, despite Ca-ionised being the gold standard. Discrepancies can occur between these measurement modalities and can lead to clinical dilemmas. It remains unclear how large these discrepancies are in older patients. This study investigated the discrepancies between Ca-ionised and Ca-albumin in geriatric patients. METHODS: This is an observational study of all geriatric patients (n = 876) in the Jeroen Bosch Hospital (January 2018 and January 2021) in whom both Ca-ionised and Ca-albumin were measured. Misclassification of calcaemic state (i.e. low, normal or high) was calculated (percentages), the measure of agreement was described using Cohen's Kappa and for the continuous data Pearson's correlation coefficient was used. Relevant categories of age and renal function were considered for effect modification effects and studied by interaction terms in a regression model. RESULTS: In one-third of the measurements, there was a misclassification. Ca-albumin measurements failed to identify 28% of hypocalcaemia. In 3.5%, hypercalcemia based on Ca-albumin was not confirmed by Ca-ionised. The correlation coefficient between Ca-ionised and Ca-albumin was 0.743 (P = 0.01) and measure of agreement by Kappa was 0.213 (P < 0.001). In the oldest old (≥ 85 years) and patients with eGFR <30 ml/min/1.73 m2 ,the agreement by Kappa was lower, with values of 0.192 and 0.104, respectively. CONCLUSION: There is a discrepancy between Ca-albumin and Ca-ionised in one-third of the geriatric patients, leading to clinical dilemmas. In the oldest old and patients with renal dysfunction, this problem is most pronounced.

Serial monitoring of ionised calcium levels in plateletpheresis donors: A study from tertiary care oncology centre in India.

BACKGROUND: Plateletpheresis is a safe procedure, and the most common reaction is hypocalcemia which is transient and self-limiting, but it can have an impact on donor experience and donor return rate. AIM: To serially monitor the ionized calcium levels of the plateletpheresis donors and to correlate with symptoms of hypocalcemia if any. METHODS: It was a prospective observational study in 126 healthy voluntary donors eligible for plateletpheresis as per the Departmental SOP and after taking written informed consent. Procedures were conducted on continuous flow centrifugation (CFC) and intermittent flow centrifugation (IFC) cell separators. Donor blood samples were collected in pre-heparinized syringes at different intervals to measure ionized calcium levels (iCa++) by venous blood gas analysis (Cobas 221). RESULTS: There was a continuous and gradual decrease in iCa++ from start to 30-45 minutes during the procedure; while the levels showed a gradual increase at end of the procedure and reached near the baseline values after 15-30 min of completion of the procedure. The change in iCa++ was statistically significant at 30 min and 45 min (p < 0.05), which was correlated with symptoms of hypocalcemia observed in 32.5 % (41/126) of the donors. Females experienced more symptoms of hypocalcemia as compared to males (p < 0.01). Donors who underwent plateletpheresis on the IFC machine experienced more symptoms of hypocalcemia as compared to the CFC machine (p < 0.05). CONCLUSION: For donors with persistent symptoms of hypocalcemia which are unrelieved by procedural modifications (reducing blood return rate, citrate infusion rate, etc.) measurement of iCa++ and administration of oral calcium tablets may be considered.

Association between ionised calcium and severity of postpartum haemorrhage: a retrospective cohort study.

BACKGROUND: Postpartum haemorrhage (PPH) is often complicated by impaired coagulation. We aimed to determine whether the level of ionised calcium (Ca2+), an essential coagulation co-factor, at diagnosis of PPH is associated with bleeding severity. METHODS: This was a retrospective cohort study of women diagnosed with PPH during vaginal delivery between January 2009 and April 2020. Ca2+ levels at PPH diagnosis were compared between women who progressed to severe PPH (primary outcome) and those with less severe bleeding. Severe PPH was defined by transfusion of ≥2 blood units, arterial embolisation or emergency surgery, admission to ICU, or death. Associations between other variables (e.g. fibrinogen concentration) and bleeding severity were also assessed. RESULTS: For 436 patients included in the analysis, hypocalcaemia was more common among patients with severe PPH (51.5% vs 10.6%, P<0.001). In a multivariable logistic regression model, Ca2+ and fibrinogen were the only parameters independently associated with PPH severity with odds ratios of 1.14 for each 10 mg dl-1 decrease in fibrinogen (95% confidence interval [CI], 1.05-1.24; P=0.002) and 1.97 for each 0.1 mmol L-1 decrease in Ca2+ (95% CI, 1.25-3.1; P=0.003). The performance of Ca2+ or fibrinogen was not significantly different (area under the curve [AUC]=0.79 [95% CI, 0.75-0.83] vs AUC=0.86 [95% CI, 0.82-0.9]; P=0.09). The addition of Ca2+ to fibrinogen improved the model, leading to AUC of 0.9 (95% CI, 0.86-0.93), P=0.03. CONCLUSIONS: Ca2+ level at the time of diagnosis of PPH was associated with risk of severe bleeding. Ca2+ monitoring may facilitate identification and treatment of high-risk patients.

Not all forms of dietary phosphorus are equal: an evaluation of postprandial phosphorus concentrations in the plasma of the cat.

Phosphorus is present in diets as naturally occurring P from raw materials or added as an inorganic salt. However, little is known about postprandial kinetics of P absorption in cats. Here, we describe several studies quantifying postprandial kinetics following the ingestion of diets of varying composition. Briefly, cats were fed a meal consisting of 50 % of their metabolic energy requirement in a randomised crossover design. A pre-meal baseline blood sample was taken via cephalic catheter and repeated measurements taken regularly up to 6 h post-meal to assess the whole blood ionised Ca, plasma P and parathyroid hormone concentrations. A diet containing 4·8 g total P/4184 kJ (1000 kcal), 3·5 g P from sodium dihydrogen phosphate (NaH2PO4)/4184 kJ (1000 kcal) and Ca:P 0·6 caused a marked increase in plasma P from baseline to a peak of 1·976 (95% CI 1·724, 2·266) mmol/l (P <0·001), whereas a diet containing 3·38 g total P/4184 kJ (1000 kcal), no added inorganic P and Ca:P 1·55 resulted in a postprandial decrease in plasma P (P = 0·008). Subsequent data indicate that added inorganic P salts in the diet above 0·5 g P/4184 kJ (1000 kcal) cause an increase in plasma P in cats, while diets below this do not. The data presented here demonstrate that sources of added inorganic P salts cause a temporary postprandial increase in plasma P in a dose-dependent manner, prolonged in diets with Ca:P <1·0. Dietary P derived from natural food ingredients (e.g. meat or vegetable matter) does not appear to have any effect on postprandial plasma P.

Intraoperative parathyroid hormone (PTH) testing in patients with primary hyperparathyroidism and PTH levels in the normal range.

BACKGROUND: Primary hyperparathyroidism is a common endocrine disorder. Hypercalcemia with normal PTH levels is very unusual and can lead to diagnostic difficulties. There are very few very few studies in the literature and all with limited numerical samples. The goal of the present study was to determine the real incidence and characteristics of primary hyperparathyroidism with normal PTH and to evaluate if intraoperative PTH testing is useful in these patients. METHODS: We performed a retrospective review of 314 patients who had undergone parathyroidectomy to treat primary hyperparathyroidism between January 2002 and December 2016. Patients were divided in two groups according to biochemical preoperative findings: in Group A were included patients with normal serum PTH, in Group B those with increased serum PTH. RESULTS: Nine patients (3.7%) were included in group A and 235 in group B. Patients in group A were younger (51.5 ± 12.9 years vs 59.6 ± 12.5); preoperative serum calcium and the incidence of coexisting thyroid disease were similar between the two groups. Symptomatic patients were more frequent in Group A (77.8% vs 39.1%; p = 0.048). There were no significant differences regarding preoperative localization studies and surgical procedure. Intraoperative PTH determination demonstrated sensitivity of 86% in group A and 97% in group B, specificity and positive predictive value of 100% in both the groups, negative predictive value of 67% in group A and 79% in group B. Histopathological examination demonstrated a single gland disease in 8 (88.9%) patients in group A and a multi gland disease in 1 (11.1%), in group B single gland disease was found in 218 (92.8%) patients and multi gland disease in 17 (7.2%). Unsuccessful surgery with persistent or recurrent hyperparathyroidism occurred in 1 (11.1%) patient in group A and 4 (1.7%) in group B. CONCLUSIONS: Primary hyperparathyroidism with normal PTH is rare but physicians should be aware of this possibility in patients with hypercalcaemia. Patients with normal PTH levels are younger and more frequently symptomatic. Intraoperative PTH testing plays an important role in the operative management even in such patients.

Serum 25-hydroxyvitamin D is associated with reduced verbal episodic memory in healthy, middle-aged and older adults.

BACKGROUND: There is increasing evidence supporting an association of higher serum vitamin D concentration with better cognitive performance in older individuals. However, to date, consideration of the putative association between vitamin D and cognition has been based principally on studies investigating clinical participant samples manifesting vitamin D deficiency, particularly in older people. Moreover, relationships between vitamin D and cognition are typically not considered in the context of counter-regulatory calcium-modulating hormones or calcium homeostasis. OBJECTIVE: Serum vitamin D/bioactive (ionised) calcium/parathyroid hormone homeostasis was considered in the context of cognitive performance in healthy, middle-aged and older individuals. DESIGN: A cross-sectional sample of 179 participants between the ages of 47-84 years was recruited for this study (114 females, 65 males). Participants provided fasting blood samples for analysis of serum 25-hydroxyvitamin D levels, ionised calcium (iCa) and parathyroid hormone (PTH) and completed cognitive measures of verbal episodic learning and memory. RESULTS: Serum 25-hydroxyvitamin D concentrations were negatively associated (with and without covariates of age, gender, depression and NART scores, iCa, and PTH) with measures of verbal episodic learning and memory, in particular with trial 5 of the Rey Auditory Verbal Learning Test (RAVLT) and long-delay free recall on the RAVLT. CONCLUSION: Overall, the findings from this study suggest an association between higher vitamin D status and poorer performance on verbal episodic memory in middle-aged and older individuals with normal vitamin D-calcium-PTH homeostasis. Despite requiring replication in other participant samples, this is a potentially important finding as it indicates that it may not be beneficial from a cognitive perspective to provide vitamin D supplements in individuals with already adequate vitamin D status.

Effect of 2 Years of Monthly Calcifediol Administration in Postmenopausal Women with Vitamin D Insufficiency.

BACKGROUND: We assessed the long-term (24 months) efficacy and safety of monthly calcifediol (0.266 mg) in the correction and maintenance of total 25(OH)D levels in postmenopausal women with basal values <30 ng/mL. METHODS: We initially enrolled 45 consecutive patients during the period September 2019-September 2020. After an initial visit, patients were instructed to return at 3, 6, 9, 12 and 24 months for measuring serum total 25(OH)D, ionised calcium, creatinine and isoenzyme of alkaline phosphatase (bALP). Here, we report only the per-protocol analysis, because the COVID-19 pandemic precluded adherence to the scheduled visits for some patients. RESULTS: The patients' mean age was 62.4 ± 9.0 years. Mean basal 25(OH)D levels were 20.5 ± 5.3 ng/mL. There was a continuous increase of mean 25(OH)D values (p for trend < 0.001). However, mean values at month 24 (36.7 ± 15.9) were not significantly different in respect to values at month 12 (41.2 ± 11.18). At 24 months, only 1 out 19 patients had a value <20 ng/mL. There was a significant decrease with time of mean values of bALP (p < 0.0216), with no significant changes between 12 and 24 months. No significant changes were observed as far as ionised calcium or creatinine were concerned. CONCLUSIONS: The long-term administration of calcifediol maintains stable and sustained 25(OH)D concentrations, with no safety concerns.

Changes in arterial pH do not explain the reductions in ionised calcium observed during COVID-19 infection.

BACKGROUND: Hypocalcaemia predicts coronavirus disease 2019 (COVID-19) severity and mortality. We hypothesized an association between respiratory alkalosis secondary to hypoxia and low ionised calcium (iCa) concentration in patients with COVID-19. METHODS: Arterial blood gas samples taken from January 2019 to March 2021 were retrospectively matched with infection status. Principal components regression was undertaken to determine the correlation between pH, partial pressure arterial oxygen (PaO2), partial pressure arterial carbon dioxide (PaCO2), and iCa. RESULTS: We included 4056 patients (300 COVID-19 detected, 19 influenza detected), corresponding to 5960 arterial blood samples. The COVID-19 detected group had a statistically significantly lower iCa, PaO2 and PaCO2, and more alkalotic pH than infection-free groups. The influenza group had a lower iCa and PaCO2, higher PaO2, and a more alkalotic pH than infection-free groups, but these differences were non-significant. Principal components regression revealed that pH, PaCO2, and PaO2 explain just 2.72 % of the variance in iCa. An increase in pH by 1 unit was associated with an iCa reduction of 0.141 â€‹mmol/L (p â€‹< â€‹0.0001). CONCLUSION: Reduction in iCa concentration in patients with COVID-19 is not associated with pH derangement. Influenza infection was associated with a minor reduction in iCa in our small sample, a hitherto unreported finding, although statistical significance was not demonstrated.

RNA in situ hybridisation as a molecular diagnostic technique targeting IBA-1 and CD204 in canine histiocytic sarcoma.

BACKGROUND: Canine histiocytic sarcoma (HS) is an aggressive cancer with morphologically variable features; therefore, obtaining a definitive diagnosis can be challenging. Two proteins, IBA-1, ionised calcium-binding adapter molecule 1, and CD204, a macrophage scavenger receptor, have been shown to be specific immunohistochemical markers helpful in distinguishing HS from other tumour types with similar morphological features. OBJECTIVES: This study was performed to demonstrate the use of RNA in situ hybridisation (ISH) technology allowing single-molecule RNA visualisation in formalin-fixed paraffin-embedded (FFPE) tissues as a molecular tool for the diagnosis of canine HS. METHODS: Reverse transcription polymerase chain reaction (RT-PCR) and western blot analysis for IBA-1 and CD204 were performed to correlate gene expression and protein expression of these two markers in the histiocytic sarcoma DH82 cell line. RNA-ISH for IBA-1 and CD204 was performed on the DH82 cell line to validate the RNA-ISH probes. RNA-ISH and immunohistochemistry (IHC) were performed in clinical HS FFPE samples to demonstrate mRNA and protein expression of IBA-1 and CD204. FFPE archived samples of canine round cell tumours, melanoma and anaplastic sarcoma were used as negative controls. RESULTS: RNA-ISH and IHC showed moderate to strong expression for IBA-1 and CD204 in the neoplastic cells in both the canine DH82 cell line and the archived canine HS samples. RNA-ISH and IHC showed scattered positive staining in the control tumours samples, consistent with macrophagic infiltration. CONCLUSION: RNA-ISH for CD204 and IBA-1 appeared to have a high specificity and sensitivity in our samples and may be an additional valuable diagnostic technique in identifying HS.

Cutaneous xanthoma causing hypercalcaemia in a cat.

CASE SUMMARY: A 5-year-old male neutered cat weighing 3.56 kg presented owing to the development of two masses over the dorsal cervical and cranial thoracic areas, as well as weight loss, inappetence and vomiting. Diagnostic tests revealed a grossly lipaemic sample with hypercholesterolaemia (440 mg/dl; reference interval [RI] 90.0-205.0), hypercalcaemia (>16.0 mg/dl [RI 8.0-11.8]) and urine specific gravity 1.022 (RI ⩾1.035). When re-presented 9 months later, fasted blood analyses revealed elevated ionised calcium (1.87 mmol/l [RI 1.11-1.38]), persistently elevated total calcium, normal phosphate and persistent minimally concentrated urine with calcium oxalate dihydrate crystals. Ultrasound-guided fine-needle aspiration of the masses produced blood-tinged purulent fluid with negative culture results. Excisional biopsies of both masses were undertaken, and histopathology was consistent with cutaneous xanthoma. No organisms were identified with special staining, and deep-tissue culture did not grow bacteria or fungi. Postoperatively, repeat fasted biochemical analysis revealed persistent hypercholesterolaemia with normal triglycerides, and normalisation of ionised and total calcium levels. Based on these findings, a diagnosis of cutaneous xanthoma causing hypercalcaemia due to primary dyslipidaemia was made. The cat was reported to be significantly improved in comfort and energy levels postoperatively and a transition to a fat-restricted diet was instituted. Eight months after xanthoma removal no recurrence was reported. RELEVANCE AND NOVEL INFORMATION: To our knowledge, this is the first report of cutaneous xanthoma and associated granulomatous inflammation causing hypercalcaemia due to dyslipidaemia in a cat. Familial hypercholesterolaemia is an example of a primary condition that could cause dyslipidaemia in cats, and further studies are warranted to better describe the genetic characteristics. Xanthoma formation and the resultant granulomatous inflammation should be considered in cases of hypercalcaemia.

Lysosomal gene Hexb displays haploinsufficiency in a knock-in mouse model of Alzheimer's disease.

Lysosomal network abnormalities are an increasingly recognised feature of Alzheimer's disease (AD), which appear early and are progressive in nature. Sandhoff disease and Tay-Sachs disease (neurological lysosomal storage diseases caused by mutations in genes that code for critical subunits of ß-hexosaminidase) result in accumulation of amyloid-ß (Aß) and related proteolytic fragments in the brain. However, experiments that determine whether mutations in genes that code for ß-hexosaminidase are risk factors for AD are currently lacking. To determine the relationship between ß-hexosaminidase and AD, we investigated whether a heterozygous deletion of Hexb, the gene that encodes the beta subunit of ß-hexosaminidase, modifies the behavioural phenotype and appearance of disease lesions in App NL-G-F/NL-G-F (App KI/KI ) mice. App KI/KI and Hexb +/- mice were crossed and evaluated in a behavioural test battery. Neuropathological hallmarks of AD and ganglioside levels in the brain were also examined. Heterozygosity of Hexb in App KI/KI mice reduced learning flexibility during the Reversal Phase of the Morris water maze. Contrary to expectation, heterozygosity of Hexb caused a small but significant decrease in amyloid beta deposition and an increase in the microglial marker IBA1 that was region- and age-specific. Hexb heterozygosity caused detectable changes in the brain and in the behaviour of an AD model mouse, consistent with previous reports that described a biochemical relationship between HEXB and AD. This study reveals that the lysosomal enzyme gene Hexb is not haplosufficient in the mouse AD brain.

Serum ionised calcium and the risk of acute respiratory failure in hospitalised patients: a single-centre cohort study in the USA.

OBJECTIVES: The objective of this study was to evaluate the risk of acute respiratory failure in all hospitalised patients based on admission serum ionised calcium. DESIGN: A retrospective cohort study. SETTING: A tertiary referral hospital in Rochester, Minnesota, USA. PARTICIPANTS: All hospitalised patients who had serum ionised calcium measurement within 24 hours of hospital admission from January 2009 to December 2013. Patients who were mechanically ventilated at admission were excluded. PREDICTORS: Admission serum ionised calcium levels was stratified into six groups: ≤4.39, 4.40-4.59, 4.60-4.79, 4.80-4.99, 5.00-5.19 and ≥5.20 mg/dL. PRIMARY OUTCOME MEASURE: The primary outcome was the development of acute respiratory failure requiring mechanical ventilation during hospitalisation. Logistic regression analysis was fit to assess the independent risk of acute respiratory failure based on various admission serum ionised calcium, using serum ionised calcium of 5.00-5.19 mg/dL as the reference group. RESULTS: Of 25 709 eligible patients, with the mean serum ionised calcium of 4.8±0.4 mg/dL, acute respiratory failure requiring mechanical ventilation occurred in 2563 patients (10%). The incidence of acute respiratory failure was lowest when admission serum ionised calcium was 5.00-5.19 mg/dL, with the progressively increased risk of acute respiratory failure with decreased serum ionised calcium. In multivariate analysis with adjustment for potential confounders, the increased risk of acute respiratory failure requiring mechanical ventilation was significantly associated with admission serum ionised calcium of ≤4.39 (OR 2.52; 95% CI 2.12 to 3.00), 4.40-4.59 (OR 1.76; 95% CI 1.49 to 2.07) and 4.60-4.79 mg/dL (OR 1.48; 95% CI 1.27 to 1.72), compared with serum ionised calcium of 5.00-5.19 mg/dL. The risk of acute respiratory failure was not significantly increased when serum ionised calcium was at least 4.80 mg/dL. CONCLUSION: The increased risk of acute respiratory failure requiring mechanical ventilation was observed when admission serum ionised calcium was lower than 4.80 mg/dL in hospitalised patients.

Coagulation factor IV is an indicator of symptomatic pulmonary embolism in patients with primary lung cancer.

BACKGROUND: Coagulation factor IV, also known as serum ionised calcium (SIC), participates in coagulative process and tends to elevate in patients with primary lung cancer. It may be an indicator of symptomatic pulmonary embolism (PE) due to primary lung cancer (LC). METHODS: A total of 388 patients who underwent CTPA and/or radionuclide ventilation perfusion scanning due to PE-suspected symptoms were stratified into LCPE (lung cancer and PE) group (n = 95), PE group (n = 99), LC group (n = 98) and control group (n = 96). At admission, the level of SIC and STC (serum total calcium) was compared among four groups. At discharge, the level change of SIC and STC from admission to discharge was compared among four groups. The coefficients analysis between SIC as well as STC and the possibility of PE were performed. RESULTS: The SIC of LCPE group was the highest among four groups at admission (P < 0.001). The level change of SIC from admission to discharge in LCPE group was the highest among four groups (P = 0.001). A ROC curve analysis demonstrated that the sensitivity and specificity of SIC for a diagnosis of PE among LC patients were 71.9% and 86.0%, respectively. The area under curve (AUC) was 0.781. Along with the increase of 0.1 mmol/L in SIC level, the risk ratio for a PE was 2.165 (1.537-2.849) (P < 0.001). CONCLUSIONS: Serum ionised calcium may be an indicator of pulmonary embolism in patients with primary lung cancer.

Increased Serum Parathyroid Hormone, Osteocalcin and Alkaline Phosphatase Are Associated with a Long-Term Adverse Cardiovascular Outcome after Coronary Artery Bypass Graft Surgery.

Despite the fact that an association of osteopoenia/osteoporosis with elevated risk of coronary artery calcification (CAC) and coronary atherosclerosis (CA) is well-established, it remains unclear whether bone turnover markers can be employed in long-term prognostication of such patients. Here we measured serum calcium, phosphate, calcitonin, parathyroid hormone (PTH), osteoprotegerin, osteocalcin, osteopontin, alkaline phosphatase and its bone isoenzyme, subsequently correlating them with an adverse cardiovascular outcome after 3 years of follow-up. The extent of brachiocephalic artery stenosis, CA, or CAC, as well as prevalence of osteopoenia/osteoporosis before the coronary artery bypass graft (CABG) surgery, did not differ between outcome groups, suggesting that subtle molecular mechanisms might be involved in determining the outcome rather than clinical or subclinical disease. After stepwise logistic regression, serum osteocalcin > 26.8 ng/mL and PTH > 49.1 pg/mL were independent predictors of an adverse outcome. Serum ionised calcium correlated with multivessel coronary artery disease; moreover, patients with severe CA (SYNTAX score > 21) had higher serum ionised calcium than those with mild CA. Likewise, serum alkaline phosphatase was associated with severe CA and CAC (Agatston score > 400). In conclusion, serum PTH, osteocalcin, and alkaline phosphatase are associated with an adverse cardiovascular outcome 3 years after CABG surgery regardless of osteopoenia/osteoporosis, coronary/peripheral atherosclerosis, and CAC.

A prospective observational study of the change in systemic ionised calcium following 4% citrate locking of venous haemodialysis catheters in intensive care patients.

Traditionally heparin has been the anticoagulant of choice for venous dialysis catheter locking. There is systemic leakage of heparin catheter locking solutions at the time of injection. Alternative agents, such as citrate, are increasingly being used. We are not aware of any data in the critical care literature on the effect of citrate locking of venous dialysis catheters on systemic ionised calcium (iCa2+). To assess the effect of 4% citrate locking of venous dialysis catheters on systemic iCa2+ in intensive care patients we performed a prospective observational study of 50 paired samples in 26 intensive care patients receiving 4% citrate dialysis catheter locking in an adult tertiary intensive care unit between May 2016 and December 2016. Arterial blood gas (ABG) analysis was performed prior to venous dialysis catheter locking and a baseline iCa2+ result obtained. The catheter was locked with 4% citrate solution. A further ABG was sampled between 30 and 120 seconds later and the iCa2+ results were compared. Patients were observed for clinical signs of hypocalcaemia. On average, there was little difference between the pre- and post-catheter locking iCa2+ (median pre-locking iCa2+ 1.19 mmol/l, mean change of +0.004 mmol/l, 95% confidence interval [CI] -0.004 to 0.013, P=0.34). There was no evidence this difference differed by length of catheter P=0.26) or site of catheter P=0.85) insertion, but there was some evidence that this differed by receipt of citrate dialysis circuit anticoagulation P=0.013). Patients who received citrate dialysis circuit anticoagulation had an increase in catheter locking iCa2+ by 0.017 mmol/l (95% CI 0.00 to 0.028). Locking of venous dialysis catheters with 4% citrate solution has no clinically significant effect on systemic iCa2+ in intensive care patients with indwelling venous dialysis catheters.

Oral vitamin D supplementation at five times the recommended allowance marginally affects serum 25-hydroxyvitamin D concentrations in dogs.

Little is known regarding optimal vitamin D status in adult dogs. To date no studies on vitamin D supplementation for improving vitamin D status have been reported for adult dogs. The aims of this study were to identify dogs with low vitamin D status and evaluate an oral dosage of cholecalciferol (D3) for effectiveness in increasing vitamin D status. For this, forty-six privately owned dogs were evaluated. Of the dogs, thirty-three (or 71·7 %) had serum 25-hydroxyvitamin D (25(OH)D) concentrations less than 100 ng/ml, a minimum previously suggested for vitamin D sufficiency in dogs. Subsequently, thirteen dogs were enrolled in a supplementation trial. Dogs were given either a D3 supplement (n 7; 2·3 µg/kg(0·75)) or olive oil placebo (n 6) daily with food. Serum concentrations of 25(OH)D were determined at weeks 1, 3 and 6, and at the trial end. Only at the trial end (weeks 9-10) was 25(OH)D significantly greater (P = 0·05) in supplemented v. placebo dogs. Serum concentrations of 24R,25-dihydroxycholecalciferol determined at the trial end were about 40 % of that of 25(OH)D3 and not significantly different between the groups. Concentrations of parathyroid hormone, ionised Ca, P and creatinine measured in initial and final serum samples indicated supplementation caused no toxicity. We conclude that vitamin D3 supplementation at a dosage near the National Research Council recommended safe-upper limit was not effective for rapidly raising serum 25(OH)D concentrations in healthy, adult dogs. Further work is needed in evaluating the metabolism of orally administered D3 in dogs before dosing recommendations can be made.

Serum ionised calcium in birth asphyxia.

Serum total and ionised calcium levels were measured at birth and at 48 hours in 25 term neonates with birth asphyxia (one minute APGAR score of 6 or less) and in 25 normal term neonates (one minute APGAR score of 7 or more). Infants were categorised into two groups TAGA (term appropriate for gestational age) and TSGA (term small for gestational age). Asphyxiated infants had significantly lower serum total and ionised calcium values at birth as well as at 48 hours. Abnormal clinical features were observed in 48% of asphyxiated infants. Low ionised calcium was detected in symptomatic babies, who had otherwise normal total calcium values. Due to hyocalcemia especially ionised calcium in asphyxiated infants and high frequency of functional derangement associated with this hypocalcemioa, serial monitoring of serum isonised calcium levels is necessary.