This is a tough symptom. We won’t discuss it much, because “Lightheadedness” is so vague, it could mean almost anything. The most common cause is Anxiety, but it could also be something like stroke, sepsis, lung disease (low oxygen), heart disease, pregnancy, diabetes, metabolic derangements (low potassium, high calcium, etc. etc.), etc. etc.
If the patient is “lightheaded” right while we’re seeing them, we check vital signs and their oxygen level (“O2 saturation”). Any abnormalities (very fast heart rate, low blood pressure, etc.) define the work-up. If heart rate & blood pressure are normal, we might check Postural Vital Signs, the difference from lying down to standing. A large change would raise concern for Dehydration, or even Shock.
We also seek specific symptoms that might localize the cause to a specific organ, & proceed from there. But if there aren’t any, and vital signs & physical exam are normal, we might order basic blood tests (Complete Blood Count for Anemia, and a Comprehensive Metabolic Panel for kidney & liver function, sugar, calcium, potassium, etc.), also a pregnancy test. If all these are normal, during the time period when the patient was actually feeling lightheaded, Anxiety remains the most likely diagnosis.
If the patient felt lightheaded recently, but not now, we can eliminate many causes that wouldn’t have gone away so quickly, like shock, lung disease, metabolic abnormalities, etc. To address Lightheadedness that’s not currently present, we need another chief symptom or clue to work off of to formulate a list of possible diagnoses. We start by seeking the serious ones:
** Lightheadedness occurring with exertion, could be heart or lung disease. We ask if at the same time they were “dizzy,” did they also feel short of breath, chest pain, nausea, or cold sweats occurring along with being “dizzy.” If only Shortness of Breath, see that topic. If any of the others too, see also Chest Pain.
** If the Lightheadedness is Postural (occurs upon arising), we review new medications which may cause this and check postural vital signs (see above). If postural symptoms are chronic, we may think of Parkinson’s or other neurological conditions; long-standing Diabetes; certain heart conditions; maybe Adrenal Insufficiency; may even occur with advanced age. At any rate, we encourage fluid intake.
** If the Lightheaded patient has a Fever, we search for serious infections (see Fever).
** Sudden feeling of about to faint – this is different from Lightheadedness. It makes us think of heart Arrhythmias, especially if there is also a sense of skipped heart beats, palpitations, or a rapid heart rate (we might teach patients how to take their pulse). We’d do an EKG, which is usually normal if there’s no symptom at the moment. Then we’d order a portable EKG (“ambulatory monitoring”), done through a patch on the chest or maybe an implant, for 2, 14, or even 28 days. We always do this for a history of fainting.
Of course, a panic attack can cause both lightheadedness and palpitations. But in that case, there’s a simultaneous sense of panic, which isn’t the case with an Arrhythmia (even though the latter may seem scary).
** Have there been falls? We inquire carefully to be sure when they say they’re “lightheaded” or “dizzy,” they don’t really mean Unsteady or Uncoordinated. We’d do a good neurological exam, including observing their gait, seeing if they can stand with feet tight together for a minute, even hop on one leg. Poor Balance / Coordination can be due to a wide variety of diseases; it’s a different work-up than “Lightheadedness.”
We’re especially concerned if Lightheadedness is brand new and continuous, with no prior history before. If the symptom is long-standing, or if it comes & goes, on & off during the day, Anxiety is most likely.
We always watch out if an elderly patient complains of new, acute dizziness (or new, acute anything, for that matter).
My best diagnosis of “dizziness” came when I was right out of school. Having no idea, I performed a thorough exam. While listening to the lungs, compulsively checking all over, my patient stopped taking the deep breaths as I’d requested, to exclaim, “My dizziness! It just came back again!” Hyperventilation, due to generalized anxiety! Simultaneous palpitations (heart pounding), and especially tingling in the hands or lips, clinches the diagnosis.
See also Lightheadedness for the clinician’s condensed thought-process when face-to-face with a patient.