The Management of Hypercholesterolemia in Patients with Neuromuscular Disorder.

PURPOSE OF REVIEW: We describe and discuss the safety of statins and non-statin drugs in neuromuscular disorders (NMDs). We also propose a pragmatic model of care for the management of such cases. RECENT FINDINGS: Patients with both NMD and hypercholesterolemia may be particularly disadvantaged owing to the toxic effects of cholesterol-lowering therapy and the inability to take medication. Specifically, the management of hypercholesterolemia in patients with NMD is complicated by the increased risk of statin-related myotoxicity and concerns that statins may aggravate or possibly induce the onset of a specific NMD. The most severe form of statin-related myotoxicity is immune-mediated necrotizing myopathy. Management of hypercholesterolemia in patients with NMDs include treating modifiable factors, consideration of toxicity risk of statin, use of non-statin lipid lowering agents, noting possible drug interactions, and careful monitoring.

Independent relationships between bone mineral density, regional body fat and insulin sensitivity in white males.

BACKGROUND: Adiposity and insulin sensitivity may affect bone mineral density (BMD), but the confounding effect of weight hinders discrimination of independent associations. We explored whether regional fat masses and insulin sensitivity are independently related to BMD. MATERIALS AND METHODS: Relationships between total and regional body fat, insulin sensitivity and measures of BMD in 8 different regions were evaluated in a cross section of 590 generally healthy, white males, 274 of whom received measurement of insulin sensitivity (Si) using the intravenous glucose tolerance test. Measurements included total, android and gynoid fat and lean body mass and regional BMDs by dual-energy X-ray absorptiometry. Linear regression analyses were combined in a mediation analysis to explore associations with each regional BMD. RESULTS: Weight correlated positively with total fat mass (R2  = 0.67, P < 0.001) and negatively with Si (R2  = 0.14, P < 0.001). Body composition measures were consistently positively related to BMD in all regions except lumbar and thoracic spine. Accounting for body weight rendered negative majority of associations between total and regional fat masses and BMDs. An independent association between android fat and spine BMD was particularly apparent. Si was positively associated with total and limb BMD (P < 0.01) specifically among exercisers. Accounting for Si diminished the associations of total fat (negative) and lean body mass (positive) with total and limb BMD. CONCLUSION: Android fat is independently negatively associated with spine BMD. Among those taking exercise, increased insulin sensitivity is associated with higher limb BMD and may underlie positive associations between lean body mass and BMD.

Skinfold thickness measurements and mortality in white males during 27.7 years of follow-up.

INTRODUCTION: Obesity is a major risk factor for mortality from a range of causes. We investigated whether skinfold measurements were associated with mortality independently of variation in body mass index (BMI). METHODS: A prospective analysis of mortality in 870 apparently healthy adult Caucasian men participating in an occupational health cohort was undertaken. At baseline, skinfold measurements were taken at biceps, triceps, iliac and subscapular sites. Derived measurements included the sum of all four skinfolds and subscapular to triceps, subscapular to iliac and BMI to iliac ratios. All-cause mortality was analysed by Cox proportional hazards modelling and death in specific mortality subcategories by competing risks analysis. RESULTS: During a mean of 27.7 years follow up, there were 303 deaths (119 cancer, 101 arteriovascular, 40 infection, 43 other). In univariable analysis, BMI was associated with all-cause, cancer, arteriovascular and other mortality and subscapular skinfold with all-cause and arteriovascular mortality. On bivariable analysis, with inclusion of BMI, subscapular skinfold ceased to be a associated with mortality but iliac skinfold emerged as strongly, negatively associated with all-cause and arteriovascular mortality. In multivariable analysis, with inclusion of age, BMI, smoking, alcohol and exercise, iliac skinfold was negatively associated with all-cause (Hazard ratio HR 0.77, 95% confidence interval CI 0.66-0.90, p = 0.002), arteriovascular (HR 0.75, 95%CI 0.58,0.97, p = 0.02) and infection (HR 0.63, 95%CI 0.42,0.94, p = 0.02) death. Among obese participants (BMI ≥ 30 kg/m2), iliac skinfold of ≤9.7 mm was associated with a six-fold increase in all-cause mortality risk. CONCLUSION: Low iliac skinfold thickness is an independent risk factor for all-cause mortality in adult white males with risk apparently concentrated among people who are obese.

Opportunistic Detection of Phytosterolaemia during Genetic Testing for FH: Case Series and Contextual Review.

BACKGROUND: Homozygous phytosterolaemia, is a rare autosomal recessive disorder which lead to severely elevated plasma levels of plant phytosterols causing an increased risk of coronary artery disease (CAD) and mimics the clinical presentation of familial hypercholesterolaemia(FH). Integration of the genetic variants for homozygous phytosterolaemia into the genetic panel for FH in clinical practice likely increases the detection of milder genetic forms of phytosterolaemia, of which the implications to clinical practice including cascade testing remain unclear. RESULTS: We report three families with pathogenic loss-of-function variants in ABCG5 and/or ABCG8, in which probands were identified incidentally when genetically testing them for FH. The proband of the first family was a 35-year-old man with a homozygous ABCG5 loss-of-function variant (c.1336C > T, p.Arg446*) causing severe phytosterolaemia and premature CAD on cardiac imaging; his younger brother was heterozygous for the same variant with mildly elevated phytosterol levels. The second family included 2 sisters (31 and 29-year-old) with digenic variants in ABCG5 (c.1336C > T, p.Arg446*) and ABCG8 (c.1269G > T, p.Glu423Asp with uncertain significance) with moderately elevated plasma phytosterol levels and premature CAD on cardiac imaging. The third family referred to a 68-year-old man and his 44-year-old daughter who were both heterozygous for a pathogenic ABCG5 variant (c.1166G > A, p.Arg389His), had mild phytosterolaemia and CAD on cardiac imaging. Treatment with ezetimibe alone or in combination with colesevelam reduced elevated plasma sitosterol and campesterol concentrations by 30 to 80%. CONCLUSION: Phytosterolaemia is specific genetic disorder that can mimic FH, cause premature atherosclerosis, and require specific pharmacotherapy. Cascade testing for pathogenic ABCG5/G8 variants can lead to earlier detection and treatment of affected family members.

Elevated remnant cholesterol and non-HDL cholesterol concentrations from real-world laboratory results: a cross-sectional study in Southeast Asians.

Introduction: Triglyceride-rich remnant lipoproteins (TRLs) are considered atherogenic due to the presence of remnant cholesterol, which is transported by apolipoprotein B. In clinical practice, the concentration of TRLs can be estimated by calculating remnant cholesterol or non-HDL cholesterol levels. Aim: This study aims to investigate the proportion of patients who have low LDL cholesterol (LDL-C) concentration but elevated remnant cholesterol concentration, stratified by the presence of hypertriglyceridaemia and ethnicity, using real-world hospital data. Our secondary aim is to investigate the proportion of patients with elevated non-HDL cholesterol levels using guideline-recommended goals. Methods: A 2-year retrospective study was conducted at a single centre, analyzing lipid blood tests of all patients, including directly measured LDL-C. Fasting for blood tests was not mandatory. Results: The study included a total of 21,605 consecutive patients with plasma lipid profiles analyzed in our hospital laboratory. The median age was 61 years. In patients with ASCVD (n = 14,704), 23.7% had an LDL-C level of <1.8 mmol/L, 11.3% had elevated remnant cholesterol concentrations at ≥0.65 mmol/L, and 48.8% were at the non-high-density lipoprotein cholesterol (non-HDL-C) goal (<2.6 mmol/L). Among patients diagnosed with atherosclerotic cardiovascular disease (ASCVD) with LDL-C levels of <1.8 mmol/L (n = 3,484), only 11.9% had high levels of remnant cholesterol, but 96% of the ASCVD patients also achieved the recommended non-HDL-C target of <2.6 mmol/L. When the LDL-C level was <1.8 mmol/L, the mean concentration of remnant cholesterol was 0.214 mmol/L when the triglyceride level was <1.7 mmol/L (n = 3,380), vs. 0.70 mmol/L when the triglyceride level was elevated (n = 724), p < 0.001. Among patients with a triglyceride level of ≥1.7 mmol/L and an LDL-C level of <.8 mmol/L, there were 254 patients with elevated remnant cholesterol concentration and 71 patients with suboptimal non-HDL levels. Malays had a higher mean remnant cholesterol concentration compared with both Chinese and Indians across all LDL-C levels, particularly in the presence of hypertriglyceridaemia. Conclusions: An elevated remnant cholesterol concentration of >0.65 mmol/L was present in 11% of all patients. The current guideline-recommended non-HDL-C goal, which uses a 0.8 mmol/L estimate of remnant cholesterol concentration, was achieved in >92% of patients, suggesting that it is unlikely to be clinically useful for the majority of our patient population except where there is concomitant hypertriglyceridaemia. Further studies are needed to establish the appropriate non-HDL-C goal or calculated remnant cholesterol concentration, paired with the LDL-C goal or otherwise, in a Southeast Asian population.

Cascade testing of children and adolescents for elevated Lp(a) in pedigrees with familial hypercholesterolaemia.

Elevated plasma lipoprotein(a) [Lp(a)] is a common, inherited condition independently causing cardiovascular disease. Recent expert recommendations suggest opportunistically testing for elevated Lp(a) during cascade testing for familial hypercholesterolaemia (FH). We investigated the effectiveness of detecting elevated Lp(a) in 103 children and adolescents who were first-degree relatives of 66 adult index FH cases as part of an established FH cascade screening program. The yield of detection of elevated Lp(a) using a threshold of ≥30 mg/dL in children and adolescents was assessed. Cascade testing from FH index cases with elevated Lp(a) ≥50 mg/dL identified 1 case of Lp(a) ≥30 mg/dL for every 2 children or adolescents tested. In contrast, opportunistic screening from index cases with FH but normal Lp(a) levels demonstrated 1 case of Lp(a) ≥30 mg/dL for every 7.5 children or adolescents tested (p < 0.001). In conclusion, cascade testing for elevated Lp(a) from index cases with FH and elevated Lp(a) is effective in identifying new cases of elevated Lp(a).

Prolonged Hypokalemia and Delayed Diagnosis of Primary Aldosteronism: Clinical Course and Risk Factors.

CONTEXT: Primary aldosteronism (PA) is a common cause of hypertension (HT). However, diagnosis is often delayed, leading to poorer clinical outcomes. Hypokalemia with HT is characteristic of PA, and is an indication for screening. OBJECTIVE: We evaluated if patients with PA had prolonged hypokalemia before diagnosis, the subsequent biochemical/clinical control, and factors associated with delayed diagnosis. METHODS: Our study included all PA patients with hypokalemia diagnosed between 2001 and 2022. Delayed diagnosis was defined as duration of hypokalemia of more than 1 year from first occurrence to first evaluation by a PA specialist. Patients were reassessed post adrenalectomy using the Primary Aldosteronism Surgery Outcomes criteria. We performed multivariable analysis to assess for factors associated with delayed diagnosis. RESULTS: Among 240 patients with PA who presented with hypokalemia, 122 (51%) patients had delayed diagnosis, with prolonged hypokalemia of median duration 4.5 years (range, 2.4-7.5 years). Patients with delayed diagnosis were older, had longer duration of HT, higher pill burden, lower renal function, and more prevalent cardiovascular disease. Factors associated with delayed diagnosis included older age, presence of hyperlipidemia, and less severe hypokalemia (serum potassium >3.0 mmol/L). Compared to patients with early diagnosis, a lower proportion of those with delayed diagnosis underwent adrenal vein sampling (73% vs 58%) (P < .05). Sixty of 118 (50.8%) nondelayed, and 39 of 122 (32.0%) patients with delayed diagnosis, underwent surgery. CONCLUSION: Despite manifestation of hypokalemia, many patients with PA fail to be promptly screened. Greater emphasis in HT guidelines, and efforts to improve awareness of PA among primary care physicians, are urgently needed.

Clinical and imaging features of women with polygenic partial lipodystrophy: a case series.

BACKGROUND: Familial partial lipodystrophy (FPLD) is an inherited disorder of white adipose tissue that causes premature cardiometabolic disease. There is no clear diagnostic criteria for FPLD, and this may explain the under-detection of this condition. AIM: This pilot study aimed to describe the clinical features of women with FPLD and to explore the value of adipose tissue measurements that could be useful in diagnosis. METHODS: In 8 women with FPLD and 4 controls, skinfold measurements, DXA and whole-body MRI were undertaken. RESULTS: Whole genome sequencing was negative for monogenic metabolic causes, but polygenic scores for partial lipodystrophy were elevated in keeping with FPLD type 1. The mean age of diagnosis of DM was 31 years in the FPLD group. Compared with controls, the FPLD group had increased HOMA-IR (10.3 vs 2.9, p = 0.028) and lower mean thigh skinfold thickness (19.5 mm vs 48.2 mm, p = 0.008). The FPLD group had lower percentage of leg fat and an increased ratio of trunk to leg fat percentage on DXA. By MRI, the FPLD group had decreased subcutaneous adipose tissue (SAT) volume in the femoral and calf regions (p < 0.01); abdominal SAT, visceral adipose tissue, and femoral and calf muscle volumes were not different from controls. CONCLUSION: Women with FPLD1 in Singapore have significant loss of adipose but not muscle tissue in lower limbs and have early onset of diabetes. Reduced thigh skinfold, and increased ratio of trunk to leg fat percentage on DXA are potentially clinically useful markers to identify FPLD1.

Xenosterolemia in clinical practice: what is in a name?

PURPOSE OF REVIEW: The aim of this study was to assess the potential value of the measurement of plasma xenosterols (or phytosterols) concentrations in clinical practice. RECENT FINDINGS: Recent genetic studies suggest that individuals with elevated plasma phytosterol concentrations due to monogenic and polygenic variants are at an increased risk of coronary artery disease. This supports early observations that elevated plasma phytosterol concentrations are per se atherogenic. SUMMARY: Measurement of plasma phytosterols can identify individuals with xenosterolemia (or phytosterolemia). This may be clinically useful in four ways: Establishing a diagnosis and informing management of patients with homozygous phytosterolemia; Providing a comprehensive differential diagnosis for familial hypercholesterolemia; Providing an index of cholesterol absorption that may inform personalized pharmacotherapy; and Informing more precise assessment of risk of cardiovascular disease.

Detection strategies for elevated lipoprotein(a): will implementation let the genie out of the bottle?

PURPOSE OF REVIEW: Elevated Lp(a) level is an important causal risk factor for atherosclerotic cardiovascular disease (ASCVD), principally coronary artery disease. Selective testing for Lp(a) is highly recommended in patients at intermediate and high risk for ASCVD. Lp(a) levels are predominantly genetically determined, and this has implications for cascade testing. RECENT FINDINGS: Recent studies show that cascade testing is effective in identifying elevated Lp(a) in close relatives of probands with high Lp(a). Apart from selective testing and cascade testing as detection strategies, some recent guidelines recommend testing of Lp(a) in all adults at least once in their lifetime and various implementation strategies have been suggested. SUMMARY: Hyper-Lp(a) is an important global health problem that can be easily detected. Hyper-Lp(a) meets all the criteria for universal screening except that there is not yet supportive evidence from clinical interventional trials showing a reduction of ASCVD events. The cost-effectiveness of the various detection and implementation strategies need to be further evaluated.

Association of Preoperative Hyponatremia With Surgical Outcomes: A Systematic Review and Meta-analysis of 32 Observational Studies.

BACKGROUND: Preoperative hyponatremia is prevalent in patients undergoing surgical procedures, but it is uncertain if hyponatremia will lead to increased risk of surgical mortality and morbidity. METHODS: A systematic search of Medline (PubMed), Embase, and Cochrane Library from inception through July 2, 2021, was performed. Full-length articles that reported on the association between surgical outcomes among adults aged ≥18 years with documented preoperative hyponatremia were included. FINDINGS: We identified 32 observational studies comprising 1 301 346 participants. All studies had low risk of bias. When adjusted for covariates, patients with hyponatremia had significantly higher odds of developing major complications (defined as a composite measure of 9 major complications) compared with patients with normal sodium concentrations (adjusted odds ratio = 1.37; 95% CI, 1.23-1.53; I2 = 78%; N = 10). Additionally, patients with preoperative hyponatremia also significantly higher hazards of early mortality (<90 days) compared with patients with normonatremia (adjusted hazard ratio = 1.27; 95% CI, 1.13-1.43; I2 = 97%; N = 10) after adjustment for covariates. Preoperative hyponatremia also had significant associations with respiratory, renal, and septic complications. In terms of prognostic performance, preoperative hyponatremia performed adequately in predicting major complications in surgical patients (area under the curve = 0.70; negative likelihood ratio, 0.90) with a specificity of 88% and a sensitivity of 25%. INTERPRETATION: Our meta-analysis suggests that preoperative hyponatremia is associated with poorer early mortality and major morbidity outcomes in surgical patients. Hyponatremia is also a specific prognosticator for major complications in surgical patients, reiterating its potential use as a clinical indicator of poor outcomes.

Comparison of existing methods of low-density lipoprotein cholesterol estimation in patients with type 2 diabetes mellitus.

Introduction: Elevated low-density lipoprotein cholesterol (LDL-C) is an important risk factor for atherosclerotic cardiovascular disease (ASCVD). Direct LDL-C measurement is not widely performed. LDL-C is routinely calculated using the Friedewald equation (FLDL), which is inaccurate at high triglyceride (TG) or low LDL-C levels. We aimed to compare this routine method with other estimation methods in patients with type 2 diabetes mellitus (T2DM), who typically have elevated TG levels and ASCVD risk. Method: We performed a retrospective cohort study on T2DM patients from a multi-institutional diabetes registry in Singapore from 2013 to 2020. LDL-C values estimated by the equations: FLDL, Martin/Hopkins (MLDL) and Sampson (SLDL) were compared using measures of agreement and correlation. Subgroup analysis comparing estimated LDL-C with directly measured LDL-C (DLDL) was conducted in patients from a single institution. Estimated LDL-C was considered discordant if LDL-C was <1.8mmol/L for the index equation and ≥1.8mmol/L for the comparator. Results: A total of 154,877 patients were included in the final analysis, and 11,475 patients in the subgroup analysis. All 3 equations demonstrated strong overall correlation and goodness-of-fit. Discordance was 4.21% for FLDL-SLDL and 6.55% for FLDL-MLDL. In the subgroup analysis, discordance was 21.57% for DLDL-FLDL, 17.31% for DLDL-SLDL and 14.44% for DLDL-MLDL. All discordance rates increased at TG levels >4.5mmol/L. Conclusion: We demonstrated strong correlations between newer methods of LDL-C estimation, FLDL, and DLDL. At higher TG concentrations, no equation performed well. The Martin/Hopkins equation had the least discordance with DLDL, and may minimise misclassification compared with the FLDL and SLDL.

Undiagnosed cardiovascular risk factors including elevated lipoprotein(a) in patients with ischaemic heart disease.

Objectives: This study aims to investigate the prevalence of undiagnosed cardiovascular risk factors in patients with ischaemic heart disease (IHD). Methods: We assessed the prevalence of previously undiagnosed cardiovascular risk factors, including elevated lipoprotein(a) [Lp(a)], among consenting patients with IHD who were admitted to hospital. Clinical information, including dietary history, from patients with newly diagnosed IHD and known IHD were compared. Results: Of the 555 patients, 82.3% were males and 48.5% of Chinese ethnicity. Overall, 13.3% were newly diagnosed with hypertension, 14.8% with hypercholesterolemia, and 5% with type 2 diabetes (T2DM). Patients with newly diagnosed IHD, compared to those with known IHD, had a higher prevalence of new diagnoses of hypercholesterolemia (29.1% vs. 2.0%, p < 0.001), hypertension (24.5% vs. 3.4%, p < 0.001) and T2DM (7.3% vs. 3.1%, p = 0.023). Active smoking was prevalent in 28.3% of patients, and higher in newly diagnosed IHD (34.1% vs. 23.2%, p = 0.005). Elevated Lp(a) of ≥120 nmol/L was detected in 15.6% of all patients, none of whom were previously diagnosed. Dietary habits of >50% of patients in both groups did not meet national recommendations for fruits, vegetables, wholegrain and oily fish intake. However, patients with known IHD had a more regular omega-3 supplement intake (23.4% vs. 10.3%, p = 0.024). Conclusion: Increased detection efforts is necessary to diagnose chronic metabolic diseases (hypertension, hypercholesterolemia, T2DM) especially among patients at high risk for IHD. Cardiovascular risk factors, in particular elevated Lp(a), smoking, and suboptimal dietary intake in patients with IHD deserve further attention.

Proton-pump inhibitor use amongst patients with severe hypomagnesemia.

Introduction: Long-term proton pump inhibitor (PPI) use has been associated with hypomagnesemia. It is unknown how frequently PPI use is implicated in patients with severe hypomagnesemia, and its clinical course or risk factors. Methods: All patients with severe hypomagnesemia from 2013 to 2016 in a tertiary center were assessed for likelihood of PPI-related hypomagnesemia using Naranjo algorithm, and we described the clinical course. The clinical characteristics of each case of PPI-related severe hypomagnesemia was compared with three controls on long-term PPI without hypomagnesemia, to assess for risk factors of developing severe hypomagnesemia. Results: Amongst 53,149 patients with serum magnesium measurements, 360 patients had severe hypomagnesemia (<0.4 mmol/L). 189 of 360 (52.5%) patients had at least possible PPI-related hypomagnesemia (128 possible, 59 probable, two definite). 49 of 189 (24.7%) patients had no other etiology for hypomagnesemia. PPI was stopped in 43 (22.8%) patients. Seventy (37.0%) patients had no indication for long-term PPI use. Hypomagnesemia resolved in most patients after supplementation, but recurrence was higher in patients who continued PPI, 69.7% versus 35.7%, p = 0.009. On multivariate analysis, risk factors for hypomagnesemia were female gender (OR 1.73; 95% CI: 1.17-2.57), diabetes mellitus (OR, 4.62; 95% CI: 3.05-7.00), low BMI (OR, 0.90; 95% CI: 0.86-0.94), high-dose PPI (OR, 1.96; 95% CI: 1.29-2.98), renal impairment (OR, 3.85; 95% CI: 2.58-5.75), and diuretic use (OR, 1.68; 95% CI: 1.09-2.61). Conclusion: In patients with severe hypomagnesemia, clinicians should consider the possibility of PPI-related hypomagnesemia and re-examine the indication for continued PPI use, or consider a lower dose.

The Inherited Hypercholesterolemias.

Inherited hypercholesterolemias include monogenic and polygenic disorders, which can be very rare (eg, cerebrotendinous xanthomatosis (CTX)) or relatively common (eg, familial combined hyperlipidemia [FCH]). In this review, we discuss familial hypercholesterolemia (FH), FH-mimics (eg, polygenic hypercholesterolemia [PH], FCH, sitosterolemia), and other inherited forms of hypercholesterolemia (eg, hyper-lipoprotein(a) levels [hyper-Lp(a)]). The prevalence, genetics, and management of inherited hypercholesterolemias are described and selected guidelines summarized.

Familial Hypercholesterolemia and Elevated Lipoprotein(a): Cascade Testing and Other Implications for Contextual Models of Care.

Elevated lipoprotein(a) [Lp(a)], a predominantly genetic disorder, is a causal risk factor for atherosclerotic cardiovascular disease (ASCVD) and calcific aortic valvular disease, particularly in patients with familial hypercholesterolemia (FH), a Tier I genomic condition. The combination from birth of the cumulative exposure to elevated plasma concentrations of both Lp(a) and low-density lipoprotein is particularly detrimental and explains the enhanced morbidity and mortality risk observed in patients with both conditions. An excellent opportunity to identify at-risk patients with hyper-Lp(a) at increased risk of ASCVD is to test for hyper-Lp(a) during cascade testing for FH. With probands having FH and hyper-Lp(a), the yield of detection of hyper-Lp(a) is 1 individual for every 2.1-2.4 relatives tested, whereas the yield of detection of both conditions is 1 individual for every 3-3.4 relatives tested. In this article, we discuss the incorporation of assessment of Lp(a) in the cascade testing in FH as a feasible and crucial part of models of care for FH. We also propose a simple management tool to help physicians identify and manage elevated Lp(a) in FH, with implications for the care of Lp(a) beyond FH, noting that the clinical use of RNA therapeutics for specifically targeting the overproduction of Lp(a) in at risk patients is still under investigation.

High Urinary Sodium Concentrations in Severe SIADH: Case Reports of 2 Patients and Literature Review.

We present two cases of severe hyponatremia secondary to syndrome of inappropriate secretion of antidiuretic hormone (SIADH) with very high urine sodium concentrations (>130 mmol/L). The first patient had hyponatremia from traumatic brain injury (TBI) while the second case had a history of recurrent SIADH triggered by various causes including gastritis. In both cases, fluid administration and/or consumption worsened the hyponatremia. Although a low urine sodium of <30 mmol/L is highly suggestive of hypovolemic hyponatremia and good response to saline infusion, there is lack of clarity of the threshold of which high urine sodium concentration can differentiate various causes of natriuresis such as SIADH, renal or cerebral salt wasting. Apart from high urine osmolality (>500 mOsm/kg), persistence of high urine sodium concentrations may be useful to predict poor response to fluid restriction in SIADH. More studies are needed to delineate treatment pathways of patients with very high urine osmolality and urine sodium concentrations in SIADH.

New Horizons: Revival of Lipoprotein (a) as a Risk Factor for Cardiovascular Disease.

The status of lipoprotein (a) [Lp(a)] as a cardiovascular risk factor has been resurrected by advances in genetics. Mendelian randomization studies show a causal link of Lp(a) with coronary artery disease (CAD), peripheral artery disease (PAD), and calcific aortic valve stenosis (CAVS). The genetics of Lp(a) is complex and extends beyond the kringle-IV type 2, as it is also dependent on ancestry. The plasma concentration of Lp(a) is determined by the hepatic production of apolipoprotein(a) [apo(a)] component of Lp(a), supporting the use of nucleic acids that inhibit the messenger RNA (mRNA) gene transcript for apo(a). Analytical barriers to measurement of Lp(a) are being addressed using isoform independent assays and a traceable standard. The association of Lp(a) and atherosclerotic cardiovascular disease is higher for myocardial infarction than PAD and CAVS. Increased risk of type 2 diabetes mellitus associated with low Lp(a) levels is perplexing and requires further investigation. The greatest advancement in Lp(a)-lowering therapies is based on using RNA therapeutics that are now being investigated in clinical trials. Proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibition lowers Lp(a) modestly, but whether cardiovascular benefit is independent of low-density lipoprotein lowering remains unclear. Opportunistic and selective testing for Lp(a) is supported by moderate evidence, with the case for universal screening premature. Modification of behavioral and clinical risk factors may be targeted to mitigate Lp(a)-mediated risk of cardiovascular disease. Clinical practice guidelines have been developed to address gaps in care of high Lp(a), but full implementation awaits the findings of clinical outcome trials using RNA-directed therapies currently underway.

Chylomicronemia through a burr hole: A case report.

Chylomicronemia has either a monogenic or multifactorial origin. Multifactorial chylomicronemia is the more common form and is due to the interaction of genetic predisposition and secondary factors such as obesity, diabetes, unhealthy diet, and medications. We report a case of a 38-year-old man who was diagnosed with multifactorial chylomicronemia following presentation with a subarachnoid hemorrhage requiring emergency surgery through a burr hole; lactescent cerebrospinal fluid mixed with blood was observed through the burr hole. The serum triglyceride concentration was 52⋅4 mmol/L with a detectable triglyceride concentration in the cerebrospinal fluid. Rapid weight gain leading to obesity and related unfavorable lifestyle factors were identified as key secondary causes of chylomicronemia. Gene testing revealed a homozygous variant in APOA5 and a heterozygous common variant in GPIHBP1. Accompanied with secondary causes, the interactions of gene and environmental conditions contribute to chylomicronemia. With aggressive medical treatment including excess weight loss, healthy diet, cessation of alcohol, and combination of anti-lipemic medications, normal plasma triglyceride levels were achieved.