I'm very skeptical of anything on a technical field like nutrition coming from a general news source like CNN. Most of what they report about fields I'm an expert in is straightforwardly incorrect, so I can only guess that they're equally incorrect about nutrition.
Even if they're correct, it's hard to find any useful information here. They mention three numbers: 150,000 IU, 50,000 IU, and 4,000 IU. The 150,000 IU and 50,000 IU examples exhibited serious symptoms, but the number mentioned a few posts up is 10,000 IU. The 4,000 IU number is mentioned in the sentence, "A 2017 study found 3% of Americans took more than the tolerable upper limit of 4,000 IU daily for adults, thus putting themselves at risk for toxicity." But there's no discussion of what symptoms would be experienced at this level of toxicity.
As I said above, if it's just restless legs, it doesn't seem unreasonable to try the dose (10,000 IU) and lower it if you experience restless legs. Obviously it's better to get a blood test, but as I said before, not everyone has access to that kind of healthcare.
Even if they're correct, it's hard to find any useful information here. They mention three numbers: 150,000 IU, 50,000 IU, and 4,000 IU. The 150,000 IU and 50,000 IU examples exhibited serious symptoms, but the number mentioned a few posts up is 10,000 IU. The 4,000 IU number is mentioned in the sentence, "A 2017 study found 3% of Americans took more than the tolerable upper limit of 4,000 IU daily for adults, thus putting themselves at risk for toxicity." But there's no discussion of what symptoms would be experienced at this level of toxicity.
As I said above, if it's just restless legs, it doesn't seem unreasonable to try the dose (10,000 IU) and lower it if you experience restless legs. Obviously it's better to get a blood test, but as I said before, not everyone has access to that kind of healthcare.