Excess Vitamin D Linked to Kidney Damage

[olga67]

Vitamin D has been reported to have a wide range of benefits. However, a recent case study indicates that excessive use of vitamin D can cause kidney damage in people who are not deficient in the vitamin.

The article was published online April 8 in the Canadian Medical Association Journal.

"The aim of this case study is to inform a wider audience that vitamin D at large doses [10,000 IU daily] in patients with normal serum vitamin D levels can lead to toxicity," first author Bourne Auguste, MD, University of Toronto, Ontario, Canada, told Medscape Medical News.

"The public should know that taking more vitamin D than is recommended does not necessarily lead to added benefit. Rather, it can lead to increased harm and specifically kidney failure," he added.

2010 guidelines from Osteoporosis Canada recommend 400–1000 IU of vitamin D daily for most adults, and 800–2000 IU daily for older adults and those at increased risk for osteoporosis. The US recommended daily intake of vitamin D for males and females between the ages of 1 and 70 years is 600 IU daily and 800 IU for those older than 70 years.

Because vitamin D has a wide therapeutic range, toxicity is rare, Auguste and colleagues note. However, as a fat-soluble vitamin, high doses of it taken for extended periods can lead to buildup.

"Many patients think of vitamin D as a simple supplement with no harm and perhaps historically overstated benefits," Auguste said. "Given that it is so readily available in various over-the-counter formulations and the perception that it has many benefits with no harm, other patients [besides the one in this case study] may be at risk for vitamin D toxicity and potentially kidney failure."

Vitamin D toxicity has a wide range of symptoms, which can delay diagnosis. Those symptoms include, among others, fatigue, high blood pressure, frequent urination, confusion, and itchiness. Early recognition of vitamin D toxicity may prevent chronic kidney damage.

"Vitamin D toxicity may go unrecognized for a long period of time, given the nonspecific symptoms patients may have on presentation. Patients may be taking over-the-counter supplements without full disclosure," Auguste explained.

Management includes careful review of prescription and over-the-counter medications, limiting exposure to sunlight, decreasing dietary and supplemental sources of vitamin D, and monitoring vitamin D levels in asymptomatic patients. Because it is fat soluble, it can take several months for levels to return to normal. In addition, after stopping vitamin D supplements, calcium levels may continue to increase before reversing.

"Clinicians should also consider adjunctive therapies beyond cessation of vitamin D and calcium supplements, such as hydroxychloroquine, glucocorticoids, and ketoconazole in those patients who are symptomatic to decrease the active form of vitamin D in the body," Auguste advised.

Supplements and Sunlight Triggered Toxicity

The reported case concerns a 54-year-old man who had recently returned from a trip to Southeast Asia, where he had spent an extended time sunbathing (6–8 hours per day for 2 weeks). Upon returning to Canada, a family physician found that his creatinine level was elevated (132 μmol/L from a baseline of 100 μmol/L). Four weeks later, despite discontinuing antihypertensive medication and diuretics, which could have caused dehydration and elevations in creatinine, the patient's creatinine level was even higher (376 μmol/L), and he was referred to a kidney specialist.

Further questioning revealed that the man had seen a naturopath who had prescribed high doses of vitamin D. Despite no known history of bone loss or vitamin D deficiency, the man took 8000–12000 IU of vitamin D daily for 2.5 years.

Workup disclosed hypercalcemia (ionized calcium, 1.48 mmol/L) and elevated levels of vitamin D (1,25-dihydroxyvitamin D3 level, 274 pmol/L; 25-hydroxyvitamin D3, 241 nmol/L). Renal biopsy results showed kidney damage (nephrosclerosis and microcalcifications without sarcoidosis or light chain deposition).

The nephrologist advised him to stop taking vitamin D supplements and to stop eating calcium-rich foods. His diuretics remained on hold, and the patient resumed taking one antihypertensive medication. At the second visit, physicians found that his levels of 1,25-dihydroxyvitamin D3 (the biologically active form of vitamin D) and calcium had continued to increase. The patient also described new-onset skin itchiness, likely due to his high calcium levels.

The patient declined to receive glucocorticoids because of concerns about weight gain. Upon starting hydroxychloroquine 400 mg daily, his calcium and vitamin D levels decreased. Almost 1 year later, his calcium and vitamin D levels returned to normal, but he has stage 3B chronic kidney disease.

medscape.com/viewarticle/91...

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[Hibs1]

If you are taking cofactors of k2 and magnesium this is highly unlikely to happen. The medical profession are ignorant of these facts. Another scaremongering article 're vitamin d. Big pharmaceutical don't like vitamin supplements as no money for them. Pure vitamins are essential too no nasty fillers as in prescriptions.

[greygoose in reply to Hibs1]

How would taking K2 and magnesium stop you over-dosing? Taking anything you don't need is a bad idea, which is why we always tell people to get tested first.

Big Pharma actually do make nutritional supplements and do make some money from them. But, any sort of pill has to have fillers. Or else you can't make it into a pill.

[Hibs1 in reply to greygoose]

The vitamin d is working to take calcium from our food to the bones and teeth with the help of k2 and magnesium so that the calcium is not going to our organs and arteries. They vitamin d is not lying there not being utilized. It only a has a half life of 24 hours.

The only 'fillers' in vitamin d and k2 should be olive or coconut oil nothing else. You never get that in a prescription d3, there is always something else. Likewise magnesium should be powder or powder in capsule with a carrier of glycine or malic. You'd have to be taking 50,000 d a day, without cofactors, for at least 6 months to get toxic and a level of at least 375nmol/L

[greygoose in reply to Hibs1]

All that you say is true, but that still doesn't mean you can't over-dose on vit D. Because you can.

[Angel_of_the_North in reply to Hibs1]

Still need to be sure to monitor levels and not overdose. I think A and D need to be in balance also

[Cooper27]

I think we should try to educate people about the dose of vitamin D that's appropriate, rather than deterring them entirely.

For example I think if you stick to the standard advice of taking 1000IU a day over winter months only, it should be fine.

A lot of people also take cod liver oil on a daily basis, which typically contains 400IU of vitamin D, and I think that sort of level should be fine.

When I first heard we should supplement vitamin D in winter many years ago, I simply popped into H&B and bought the first bottle I came across, which turned out to be 10,000 IU - it's a bit dangerous to be able to buy that sort of dose without anyone in the store questioning it.

[spongecat]

Precisely the reason why I do the Vitamin D (25-OH) blood spot test every spring and autumn to calculate my dose needed for that season.

I did a test in the spring and it came back at 93 nmol/L so I thought I would dose at 1000iu for the summer and sloth around in the sun a bit (when it was out!).

Just had my autumn test back and it's gone down to 65. Well that idea was a fail! So for the winter I will take 3000iu and test again in April.

I guess that 2000iu is probably going to be a better maintenance dose in the summer.

[penny]

Dr Coimbra has been using high doses of Vit D to successfully treat autoimmune conditions for 20 years. His protocol includes continuous monitoring and a dietary restrictions. He uses doses up to 300,000iu per day.