Calcium-alkali syndrome in the modern era

Metabolic Alkalosis Pathogenesis, Diagnosis, and Treatment: Core Curriculum 2022

Metabolic alkalosis is a widespread acid-base disturbance, especially in hospitalized patients. It is characterized by the primary elevation of serum bicarbonate and arterial pH, along with a compensatory increase in Pco2 consequent to adaptive hypoventilation. The pathogenesis of metabolic alkalosis involves either a loss of fixed acid or a net accumulation of bicarbonate within the extracellular fluid. The loss of acid may be via the gastrointestinal tract or the kidney, whereas the sources of excess alkali may be via oral or parenteral alkali intake. Severe metabolic alkalosis in critically ill patients-arterial blood pH of 7.55 or higher-is associated with significantly increased mortality rate. The kidney is equipped with sophisticated mechanisms to avert the generation or the persistence (maintenance) of metabolic alkalosis by enhancing bicarbonate excretion. These mechanisms include increased filtration as well as decreased absorption and enhanced secretion of bicarbonate by specialized transporters in specific nephron segments. Factors that interfere with these mechanisms will impair the ability of the kidney to eliminate excess bicarbonate, therefore promoting the generation or impairing the correction of metabolic alkalosis. These factors include volume contraction, low glomerular filtration rate, potassium deficiency, hypochloremia, aldosterone excess, and elevated arterial carbon dioxide. Major clinical states are associated with metabolic alkalosis, including vomiting, aldosterone or cortisol excess, licorice ingestion, chloruretic diuretics, excess calcium alkali ingestion, and genetic diseases such as Bartter syndrome, Gitelman syndrome, and cystic fibrosis. In this installment in the AJKD Core Curriculum in Nephrology, we will review the pathogenesis of metabolic alkalosis; appraise the precipitating events; and discuss clinical presentations, diagnoses, and treatments of metabolic alkalosis.

Case Report: Acute Kidney Injury Due to Chronic Milk-Alkali Syndrome in a Patient With Colon Cancer

Background

Common causes of hypercalcemia include primary hyperparathyroidism and paraneoplastic syndrome of malignancy. Because of this, physicians can easily miss extrinsic causes of hypercalcemia such as milk-alkali syndrome in patients with cancer. We successfully treated a case of acute kidney injury due to severe hypercalcemia caused by milk-alkali syndrome due to long-term milk drinking in a patient with colon cancer.

Case Description

A 62-year-old man was referred to nephrology for hypercalcemia and azotemia that was found during preoperative evaluation for colon cancer surgery. The patient had experienced several months of dizziness and anorexia. We started hemodialysis because hypercalcemia and azotemia were not improved despite large amounts of hydration and diuretics. We suspected paraneoplastic syndrome because of concomitant colon cancer and low intact parathyroid hormone (PTH). Renal microcalcifications were observed on ultrasonography. Metastatic calcifications of the lung and stomach were present, but no malignant metastasis appeared on bone scans. There was no evidence of metastatic malignant lesions on chest or abdominal enhanced computed tomography. PTH-related peptide was not detected. Thus, other causes of hypercalcemia beyond malignancy were considered. On history-taking, the patient reported consuming 1,000 to 1,200 mL of milk daily for the prior 3 months. Hypercalcemia was due to chronic milk-alkali syndrome. We advised withdrawal of milk and nutritional pills. Hemodialysis was stopped after 2 weeks since azotemia and hypercalcemia were resolving. Acute kidney injury was improved, and mild hypercalcemia remained when he underwent hemicolectomy after 1 month. Thereafter, serum calcium and creatinine remained normal at discharge and follow-up for 1 year in the outpatient clinic. However, lung calcifications still remained on bone scan after 1 year.

Conclusions

Chronic milk-alkali syndrome is a rare condition resulting from excessive calcium and alkali intake through various routes, like milk, nutritional supplements, and medicines for osteoporosis. Therefore, early management for hypercalcemia should include precise history taking including diet, previous diagnoses, and current medications.

Calcium Alkali Syndrome Treated With Hemodialysis

Malignancy, primary hyperparathyroidism, and vitamin D intoxication are the most common causes of hypercalcemia. Symptoms of hypercalcemia are nonspecific and require a plasma calcium level to diagnose. Undiagnosed hypercalcemia can cause renal failure long-term. Here, we describe a unique case of hypercalcemia resulting in acute kidney injury (AKI) secondary to overconsumption of calcium carbonate (Tums).

Disorders of Calcium Metabolism: Hypocalcemia and Hypercalcemia

Calcium (Ca⁺²) is a divalent cation that plays a critical role in numerous body functions such as skeletal mineralization, signal transduction, nerve conduction, muscle contraction, and blood coagulation. Ca⁺² metabolism is linked to magnesium (Mg⁺²) and phosphate metabolism. Ca⁺² homeostasis is dependent on intestinal absorption, bone turnover, and renal reabsorption. The hormonal regulators of these processes are the parathyroid hormone (PTH), calcitriol {1,25-dihydroxyvitamin D [1,25(OH)₂D]}, and serum ionized Ca⁺². Cloning of the Ca⁺²-sensing receptor (CaSR) has greatly advanced the understanding of Ca⁺² metabolism. Disorders of Ca⁺² metabolism are easily recognized because Ca⁺² is included in routine chemistry panels. Measurement of ionized Ca⁺² is the preferred way to ascertain the diagnosis of hypocalcemia and hypercalcemia.

Calcium Alkali Thiazide Syndrome: What We Need to Know

Depending on each institution's laboratory test, mean serum calcium levels range between 8.8 and 10.8 mg/dL and hypercalcemia is defined as two standard deviations above the mean. According to recent epidemiological studies, 90% of cases of hypercalcemia are due to hyperparathyroidism or malignancy. Milk Alkali syndrome (MAS) also known as Calcium Alkali syndrome (CAS) is the third biggest cause of hypercalcemia, but its incidence seems to be higher than previously thought. Here we present a case of Calcium Alkali Thiazide syndrome (CATS) in a 57-year-old female who was on calcium and vitamin D supplements (after parathyroidectomy) while also taking thiazide diuretic for hypertension. She was brought to the ED with nausea, vomiting, confusion, difficulty walking along with numbness in extremities. She had parathyroidectomy three weeks ago. During history taking, patient reported intake of calcium carbonate 1 g three times daily, calcitriol 0.5 mcg twice daily, cholecalciferol (vitamin D3) 10,000 units once daily, chlorthalidone 25 mg once daily and irbesartan 300 mg once daily. At admission, her calcium level was 23 mg/dL, ionized calcium 12.03 mg/dL, pH was 7.59 and HCO3 was 33. She was in renal failure with creatinine of 1.9 mg/dL (baseline 0.8 mg/dL). Her parathyroid hormone (PTH) level was 0. A diagnosis of CATS was made. She was treated with intravenous fluids and furosemide and discharged home on hospital day 5 after her calcium and creatinine levels normalized. A triad of hypercalcemia, acute kidney injury and metabolic alkalosis comprises MAS. Traditional MAS was caused by "Sippy diet" (containing milk and alkali) used for the treatment of peptic ulcer disease. Over the decades, the same triad of symptoms occurred in patients using excess calcium and vitamin D, hence changing the name to CAS. A subset of patients at risk for CAS also use thiazide diuretics for hypertension, making them more vulnerable to hypercalcemia and acute kidney injury. In such subset of patients, it is preferable to use the term CATS rather than MAS or CAS.

A 39 year-old woman with milk-alkali syndrome complicated by posterior reversible encephalopathy syndrome

Milk-alkali syndrome (MAS) is characterized by the triad of hypercalcemia, metabolic alkalosis, and acute kidney injury. Once thought to be a rare condition, there has been a resurgence of cases due to the consumption of calcium-containing supplements for osteoporosis prevention and dyspepsia in the general population. We describe the case of a female who presented with acute encephalopathy, hypercalcemia, and new-onset seizure. An extensive hypercalcemia workup and ruling out of other causes led to the diagnosis of MAS from excessive intake of calcium carbonate. Brain magnetic resonance imaging revealed signal abnormalities in the occipital and posterior parietal lobes that were indicative of posterior reversible encephalopathy syndrome. The patient's encephalopathy resolved after treatment of her hypercalcemia with fluid resuscitation and cessation of her calcium supplements. We present our case to highlight this unusual presentation of MAS, challenges in diagnosis, and briefly discuss the pathophysiology underlying hypercalcemia-induced encephalopathy.

Milk-alkali syndrome: a 'quick ease' or a 'long-lasting problem'

SUMMARY

We report the case of a 65-year-old female who presented with symptomatic hypercalcaemia (corrected calcium of 4.57 mmol/L) with confusion, myalgias and abdominal discomfort. She had a concomitant metabolic alkalosis (pH 7.46, HCO3- 40 mmol/L, pCO2 54.6 mmHg). A history of significant Quick-Eze use (a calcium carbonate based antacid) for abdominal discomfort, for 2 weeks prior to presentation, suggested a diagnosis of milk-alkali syndrome (MAS). Further investigations did not demonstrate malignancy or primary hyperparathyroidism. Following management with i.v. fluid rehydration and a single dose of i.v. bisphosphonate, she developed symptomatic hypocalcaemia requiring oral and parenteral calcium replacement. She was discharged from the hospital with stable biochemistry on follow-up. This case demonstrates the importance of a detailed history in the diagnosis of severe hypercalcaemia, with MAS representing the third most common cause of hypercalcaemia. We discuss its pathophysiology and clinical importance, which can often present with severe hypercalcaemia that can respond precipitously to calcium-lowering therapy.

LEARNING POINTS

Milk-alkali syndrome is an often unrecognised cause for hypercalcaemia, but is the third most common cause of admission for hypercalcaemia. Calcium ingestion leading to MAS can occur at intakes as low as 1.0-1.5 g per day in those with risk factors. Early recognition of this syndrome can avoid the use of calcium-lowering therapy such as bisphosphonates which can precipitate hypocalcaemia.

Hypercalcemic Crisis in a Patient with Post-Surgical Hypoparathyroidism

Calcium alkali syndrome (CAS), a relatively unusual etiology of hypercalcemia, is characterized by a classical triad of hypercalcemia, azotemia, and metabolic alkalosis. This condition has been described in patients who have taken an excess dose of calcium with an alkali or with a volume-depletion status. To diagnose CAS it requires a high index of suspicion and a detailed history of medication/supplement intake specifically for calcium-containing drugs and a history of all possible ingested alkali. We reported a case of post-surgical hypoparathyroidism whom later on was presented with hypercalcemic crisis due to CAS. The proposed mechanism of CAS and management are also included.

Severe hypercalcaemia due to household cleaner ingestion

We report the case of a 59-year-old man with a history of type 2 diabetes, hypertension and chronic kidney disease who presented with symptomatic severe hypercalcaemia (calcium 15.8 mg/dL) and acute kidney injury. Evaluation revealed that the hypercalcaemia was not mediated by parathyroid hormone (PTH), PTH-related peptide or 1,25-hydroxyvitamin D. Adrenal insufficiency was subsequently diagnosed and was initially thought to be the aetiology of the hypercalcaemia. He was treated with intravenous fluid, pamidronate and started on hydrocortisone with resolution of his hypercalcaemia. Over the next several months, despite adherence to hydrocortisone therapy, the patient continued to have recurrent severe hypercalcaemia requiring hospitalisation. Additional laboratory evaluation showed similar results to the initial evaluation. On further questioning, the patient admitted to routinely ingesting the household cleaning product Comet, which contains a large amount of calcium. Psychiatric assessment confirmed the diagnosis of pica. The patient eventually discontinued ingestion of Comet with resolution of his hypercalcaemia.

Small changes in calcium replacement therapy triggering hypercalcaemia and rising creatinine - a case series

In this article, we present four cases of renal failure secondary to hypercalcaemia which were brought to the attention of our hospital's nephrology team. These happened in the setting of simple medication changes for hypoparathyroidism post-thyroid surgery. These cases have in common minor changes in preparations leading to significant adverse events. In two cases, excipient changes were the only changes identified in the patients' regimen. In all cases, cessation of the offending calcium preparation and treatment with IV rehydration led to a return to baseline creatinine levels. Communicating to patients the importance of consistency in how calcium and vitamin D supplements are taken is crucial in preventing adverse effects. Prescribers should be aware of excipient changes and that these are not always clinically insignificant.

Acute milk-alkali syndrome

A 74-year-old woman presented with progressive lethargy, confusion, poor appetite and abdominal pain. She was found to have non-PTH-mediated severe hypercalcemia with renal failure and metabolic alkalosis. Extensive workup for hypercalcemia to rule out alternate etiology was unrevealing. Upon further questioning, she was taking excess calcium carbonate (Tums) for her worsening heartburn. She was diagnosed with milk-alkali syndrome (MAS). Her hypercalcemia and alkalosis recovered completely with aggressive hydration along with improvement in her renal function. High index of suspicion should be maintained and history of drug and supplements, especially calcium ingestion, should be routinely asked in patients presenting with hypercalcemia to timely diagnose MAS and prevent unnecessary tests and treatments.

Learning points:

Suspect milk-alkali syndrome in patients with hypercalcemia, metabolic alkalosis and renal failure, especially in context of ingestion of excess calcium-containing supplements.

Careful history of over-the-counter medications, supplements and diet is crucial to diagnose milk-alkali syndrome.

Milk-alkali syndrome may cause severe hypercalcemia in up to 25–30% of cases.

A Case of Hypercalcemia after Thyroidectomy

Total thyroidectomy is complicated by hypoparathyroidism in 1-3% of patients. Hypoparathyroidism is treated with oral calcium and vitamin-D supplements. Everyday use of calcium and vitamin D can lead sometimes to hypercalcemia. Ingestion of large amounts of calcium and absorbable alkali that cause hypercalcemia, various degrees of renal failure, and metabolic alkalosis, can be associated with a diagnosis of calcium-alkali syndrome. This syndrome was first identified as milkalkali syndrome, after treatment of peptic ulcer disease with milk and alkali which was widely adopted at the beginning of the 20th century. With the introduction of histamine-2 blockers and proton pump inhibitors, the occurrence of milk-alkali syndrome became rare; however, it has emerged recently as calcium-alkali syndrome because of the wide availability and increasing use of calcium carbonate, mostly for osteoporosis prevention. We present a female patient with hypoparathyroidism who presented with hypercalcemia and alkalosis as a result of treatment with calcium carbonate, vitamin D and thiazide diuretic. The patient was treated successfully by discontinuation of the above drugs, intravenous fluid administration and enhancement of calcium renal excretion. Hypercalcemia presenting as calcium-alkali syndrome is a diagnosis that requires a high index of suspicion in order to quickly identify the disorder and initiate appropriate therapy. It is important for clinicians to keep the syndrome on their list of differential diagnosis.

Hypercalcemia as a Cause of Kidney Failure: Case Report

BACKGROUND:

Hypercalcemia is a common manifestation in clinical practice and occurs as a result of primary hyperparathyroidism, malignancy, milk-alkali syndrome, hyper or hypothyroidism, sarcoidosis and other known and unknown causes. Patients with milk-alkali syndrome typically are presented with renal failure, hypercalcemia, and metabolic alkalosis caused by the ingestion of calcium and absorbable alkali. This syndrome is caused by high intake of milk and sodium bicarbonate.

CASE PRESENTATION:

We present a 28-year old male admitted to hospital with a one-month history of nausea, vomiting, epigastric pain, increased blood pressure and worsening of renal function with hypercalcemia. His serum PTH level was almost undetectable; he had mild alkalosis, renal failure with eGFR of 42 ml/min, anemia, hypertension and abnormal ECG with shortened QT interval and ST elevation in V1-V4. He had a positive medical history for calcium-containing antacids intake and after ruling out primary hyperparathyroidism, malignancy, multiple myelomas, sarcoidosis, and thyroid dysfunction, it seemed plausible to diagnose him as having the milk-alkali syndrome.

CONCLUSION:

Although milk-alkali syndrome currently may be more probably a result of calcium and vitamin D intake in postmenopausal women, or in elderly men with reduced kidney function taking calcium-containing medications, one should not exclude the possibility of its appearance in younger patients taking calcium-containing medications and consider it a serious condition taking into account its possibility of inducing renal insufficiency.

Drugs influencing acid base balance and bicarbonate concentration readings

Serum bicarbonate dosage is sensitive to pharmacological interferences. However, elevated bicarbonate concentration reflects chronic hypoventilation and has been proposed as a simple marker for screening patients with Obesity Hypoventilation Syndrome (OHS), a currently underdiagnosed multimorbid and high mortality disease. We provide a practical overview of the different drugs acting on the acid-base equilibrium to aid clinicians to interpret bicarbonate concentration readings. Little is known about the chronic impact of the usual doses of these drugs on serum bicarbonate concentration and further studies are needed. It is essential to take into account drugs that could interfere with this parameter to avoid misinterpretation of serum bicarbonate levels.

Hypercalcemia. Pathophysiological Aspects

The metabolic pathways that contribute to maintain serum calcium concentration in narrow physiological range include the bone remodeling process, intestinal absorption and renal tubule resorption. Dysbalance in these regulations may lead to hyper- or hypocalcemia. Hypercalcemia is a potentionally life-threatening and relatively common clinical problem, which is mostly associated with hyperparathyroidism and/or malignant diseases (90 %). Scarce causes of hypercalcemia involve renal failure, kidney transplantation, endocrinopathies, granulomatous diseases, and the long-term treatment with some pharmaceuticals (vitamin D, retinoic acid, lithium). Genetic causes of hypercalcemia involve familial hypocalciuric hypercalcemia associated with an inactivation mutation in the calcium sensing receptor gene and/or a mutation in the CYP24A1 gene. Furthermore, hypercalcemia accompanying primary hyperparathyroidism, which develops as part of multiple endocrine neoplasia (MEN1 and MEN2), is also genetically determined. In this review mechanisms of hypercalcemia are discussed. The objective of this article is a review of hypercalcemia obtained from a Medline bibliographic search.

Effects of potassium diformate on the gastric function of weaning piglets

Potassium diformate (KDF), as an acidifier, has been shown to improve growth performance in pigs, but it is not yet known whether KDF regulates gastric function. Thus, the objective of the present study was to investigate the effects of dietary KDF on gastric function in weaning piglets. One hundred and eighty Landrace × Large White piglets (bodyweight = 5.80 ± 0.15 kg) were weaned at 28 days old and randomly allocated into two groups, with six pens in each group and 15 piglets in each pen. Piglets in the control group were fed the basal diet, whereas the KDF-treated group was fed the basal diet supplemented with 10 g/kg KDF. After 35 days of feeding, the KDF treatment improved the bodyweight (P = 0.034) and reduced the relative weight of stomach (P = 0.050), decreased the hydrochloric acid concentration (P = 0.016) in the gastric digesta and the pepsin activity in the gastric oxyntic mucosa (P = 0.001) and increased the lactic acid concentration (P = 0.001) in the gastric digesta. Furthermore, KDF treatment increased the level of somatostatin (SS) (P = 0.009), but did not change the concentration of gastrin (P = 0.497) and the activity of H+-K+-ATPase (P = 0.575) in the gastric oxyntic mucosa. However, KDF treatment downregulated the expression of SS mRNA in the gastric oxyntic mucosa (P = 0.031) and upregulated the mRNA expression of gastrin (P < 0.001) and H+-K+-ATPase (P < 0.001) in the gastric oxyntic mucosa. These results suggest that the effects of KDF on weaning piglets may be related to the regulation of gastric function gene expression.

Calcium supplementation increases blood creatinine concentration in a randomized controlled trial

Background

Calcium supplements are widely used among older adults for osteoporosis prevention and treatment. However, their effect on creatinine levels and kidney function has not been well studied.

Methods

We investigated the effect of calcium supplementation on blood creatinine concentration in a randomized controlled trial of colorectal adenoma chemoprevention conducted between 2004–2013 at 11 clinical centers in the United States. Healthy participants (N = 1,675) aged 45–75 with a history of colorectal adenoma were assigned to daily supplementation with calcium (1200 mg, as carbonate), vitamin D₃ (1000 IU), both, or placebo for three or five years. Changes in blood creatinine and total calcium concentration were measured after one year of treatment and multiple linear regression was used to estimate effects on creatinine concentrations.

Results

After one year of treatment, blood creatinine was 0.013±0.006 mg/dL higher on average among participants randomized to calcium compared to placebo after adjustment for other determinants of creatinine (P = 0.03). However, the effect of calcium treatment appeared to be larger among participants who consumed the most alcohol (2–6 drinks/day) or whose estimated glomerular filtration rate (eGFR) was less than 60 ml/min/1.73 m² at baseline. The effect of calcium treatment on creatinine was only partially mediated by a concomitant increase in blood total calcium concentration and was independent of randomized vitamin D treatment. There did not appear to be further increases in creatinine after the first year of calcium treatment.

Conclusions

Among healthy adults participating in a randomized clinical trial, daily supplementation with 1200 mg of elemental calcium caused a small increase in blood creatinine. If confirmed, this finding may have implications for clinical and public health recommendations for calcium supplementation.

Trial Registration

ClinicalTrials.gov NCT00153816