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Which organ is lithium affecting, given the sign in the stem?
More, if you want it
Which part of the body troubles the patient after years of lithium?Tap a term: its definition, what you can do with it, and how often the exam asks it.
Definition: a kidney that responds poorly to ADH and passes large volumes of dilute urine.
You can: Tell nephrogenic diabetes insipidus from acute lithium toxicity by the long course and the absence of diarrhoea.
Definition: a slow loss of kidney function after long-term lithium.
You can: Tell renal failure from nephrogenic diabetes insipidus by a slow fall in kidney function on blood tests.
Definition: an overactive parathyroid gland that raises blood calcium.
You can: Tell hyperparathyroidism from nephrogenic diabetes insipidus by added bone pain, kidney stones and low mood.
Definition: an underactive thyroid gland that causes tiredness and low mood.
You can: Tell hypothyroidism from depression by thyroid blood tests.
Definition: a second-degree heart block with dropped beats on the ECG.
You can: Tell Wenckebach heart block from Wolff-Parkinson-White syndrome by whether lithium causes the ECG pattern.
Definition: a scaly skin disease that lithium can trigger or worsen.
You can: Name psoriasis as a lithium effect when scaly skin patches start or flare on lithium.
Definition: a spot-forming skin disease that lithium can worsen.
You can: Name acne as a lithium effect when spots worsen on lithium.
Each card is one term. The grey line is what the patient says, which is what the question stem gives.
Summary
Nephrogenic diabetes insipidus is a kidney problem in which the kidney responds poorly to ADH and cannot concentrate urine.
Nephrogenic diabetes insipidus is a kidney problem in which the kidney responds poorly to ADH and cannot concentrate urine. ADH, or antidiuretic hormone, normally tells the kidney to keep water. Long-term lithium commonly causes nephrogenic diabetes insipidus, presenting with polyuria and . The patient feels thirsty and passes large volumes of urine.
The cause runs in short steps:
The urine-concentrating defect usually recovers in the short to medium term. After many years of lithium, the kidney effects may become permanent. Lithium appears to block the action of ADH on the kidney tubule. Uraemia and nephrotic syndrome are also wrong answers here.
Margaret attends a lithium monitoring clinic after many years on lithium. Margaret says, "I drink all day and I am up all night to pass water."
Lithium can also cause . In renal failure, kidney function falls slowly over years on blood tests.
Long-term lithium can slowly impair kidney function. Some clinicians call the slow rise in creatinine creatinine creep. Some of the damage is reversible and some is permanent.
Candidates read thirst and heavy urine on lithium as toxicity. Acute lithium toxicity brings gut and nerve signs, such as vomiting, diarrhoea and coarse tremor. Thirst and polyuria after years of lithium, without diarrhoea, point to nephrogenic diabetes insipidus.
Analogy
The collecting tubule is a water pipe with taps. Aquaporins are the taps that return water to the body. ADH is the hand that turns the taps on. Lithium removes taps, so the hand turns empty handles. Water runs to the drain as dilute urine.
Where the analogy breaks: a plumber can refit a tap, while after many years of lithium the kidney loss may be permanent.
6 more sections on Lithium organ effects: nephrogenic diabetes insipidus, hyperparathyroidism, hypothyroidism, heart block and more
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